I've seen people argue that Finn's sacrifice would've worked:
There is nothing about the scene that indicates Finn won't succeed. We are told it's a suicidal run, and that is made clear through imagery. A suicidal run doesn't imply it won't work, it merely implies Finn will go down with the laser.
The idea that Finn won't take out the laser is headcanon meant to post-rationalize Rose's actions since they don't make logical sense when considered alongside her dialogue. The speeder falling apart on the approach doesn't mean it wouldn't have succeeded. The outcome could have been written either way. We've all seen movies where demolished cars skid across the finish line. We've all seen Randy Quaid fly into that alien laser in ID. Regardless, the "it wouldn't have worked" stance is a sci-fi answer to the problem, that requires understanding of the physical properties of the speeder, the operations of the laser, etc. Stuff that can't be presented in a film. This is a narrative problem. When Rose saves Finn, she tells him he shouldn't be destroying what he hates. The implication if we are supposed to view Finn's attempt as destined to fail is that Finn hate's himself, as that is all he was going to destroy... it doesn't fit with the emotional or thematic direction of the scene at all.
Here's the ship immediately before it is knocked away from the laser, still in tact:
The pieces we saw fall off were fringe pieces (ski, tiny gun). They would not have contributed to damaging the laser on impact. We specifically see the gun fall off because that is the piece that would have destroyed the cannon without Finn having to suicide. Now that it is gone, he has only one option
We can also interpret the pieces falling off of the ship as dramatic effect, since dramatic shots such as red sweaty Finn and gold laser lens flare are interspersed while we cut to heavenly music.
This scene is shot and scored just like every heroic sacrifice scene in every action movie is shot and scored. Given Rian's propensity for subversion and jerking the audience around with character deaths throughout this movie, this is most certainly intentional.
Here's the ship's position as it is knocked away:
Based on the size of the craft, I'll be generous and say he's 40 meters from impact. Assuming these clunky old ski speeders can go no faster than a speeder bike (unlikely), Finn is at most .3 seconds from impact. It's hard to believe his speeder was going to disintegrate in a fraction of a second.
And I hate digging into meters and seconds and crap, but this isn't about nitpicking tech specs. This is the only way to quantify what people are seeing on screen; why they visually believe Finn would have succeeded
If Rose had not intervened, this scene could easily have concluded with the speeder making impact. It could also have concluded with the speeder disintegrating, but from what I'm seeing, that would've looked much more out of place. It's certainly no forgone conclusion that Finn would have failed.
It could have been written either way
To top this off, Finn's speeder survives a collision with Rose and a collision with Crait, to the point that Finn is perfectly unharmed once the speeder comes to a stop. Those collisions make good, solid, loud crunching noises. This reinforces the idea that the structural integrity of the speeder was in tact .3 seconds away from impact in the audience's mind.
Bare in mind the audience has no frame of reference for how hot that pre-laser charge light thing is. Hell, they don't have a frame of reference for what it is. They also don't have any understanding of the temperature at which the speeder would melt, the force required to destroy the laser on collision, etc. None of this is part of the movie. What they understand is that the laser is deadly when it fires, and they don't see the laser fire until Finn has had time to walk away from the crash and help Rose. They also understand the laser has a weak point down the barrel
But aren't we told it won't work? Here's the full dialogue:
Rose - "There it is, that is a big gun"
- target in sight
Finn – "Okay it's heavily armored, our only shot is right down the throat. The cannon's opening, this is our chance"
- The cannon has a weak point, in a series that is famous for technological behemoths being taken down by small craft targeting a weak point, this tell's the audience something. Finn is aware of the weak point and is on a mission
Poe – "They're picking us all off, we're not gonna make it"
- Poe gives the audience information here that Finn will prove wrong. Finn does indeed make it to the cannon. Thus the audience can already find Poe's future assessments questionable
- Poe seems to be concerned about the lives of his pilots, this make sense given his failure at the beginning of the movie. It fits his arc
Finn – "allright, making my final approach, target in sight, guns are hot"
- Finn is still determined to succeed, this makes sense given Finn's arc. Finn intends to use his guns
Poe – "no, pull off, <what?> the cannon is charged, it's a suicide run. All craft pull away
- The reason given to pull away is that this is a "suicide run". This does not implicate failure, it merely implicates that the heroes will not survive if they succeed. Why is it a suicide run? We will later be shown that Finn's guns melt in the pre-laser charge. This dialogue is purposely crafted. Poe knows the only way to take out the cannons without guns is a suicide collision
- This fits with Poe's arc. We can interpret this as Poe assessing that success is not worth the lives of his crew, thus he has grown since the beginning of the film
Finn – "no I'm almost there!"
- He was </Ron Howard>
- Finn is not phased that this is a suicide run, fits his arc
Poe – "retreat Finn, that's an order"
- Told to retreat, no further reason given, fall back to prior reason, Poe does not want Finn to die
Rose – "Finn, it's too late, don't do this"
- Told it is too late, the audience sees that it is not. The cannon has not yet fired. The rebels are still protected by the blast door. Once again, the audience is questioning what they are hearing
Finn – "No! I won't let them win!"
- Finn does not want the FO to win, if they win the rebellion will end here on Crait. Still perfectly fits his arc
Rose – "No! Finn, listen to Poe, we have to retreat!"
- Do what Poe says, we have retreat. Once again, no reason given. Poe and Rose do not want Finn to die
We are simply told Finn must retreat. As happens often in this film, we see the opposite
At no point are we told Finn won't succeed, that the cannon can't be destroyed, that this won't work. The crux of this dialogue seems to be that Finn will die and his friends don't want him to die. This interpretation fits well with Poe repenting for losing his original squadron as well as with Rose's "I saved you dummy, save what you love" dialogue. It also fits well with Finn's arc, that he would be sacrificing himself to buy the rebels the time they need
Finally, Rose's stated reasoning for why she stopped Finn is "I saved you dummy, that's how we win, not fighting what we hate, saving what we love". None of this indicates Finn wouldn't have hit the gun. Rather, it indicates that Rose didn't want him to die, would prefer he live than he go down fighting.
Isn't the point of the scene to show that Finn is now selfless and devoted to a cause, whereas he began the movie wanting nothing to do with the rebellion and only wanting to find Rey? If this scene is meant to show Finn has grown, how has he grown if his motivations for destroying the cannon aren't for the greater good of the rebellion? Or even worse, if he's too dumb to understand what he's attempting won't work? How does this tie in with his decree that he is now "Rebel Scum"? I think it's clear the scene wanted to have it's cake and eat it too. Wanted to show that Finn has grown, is now selfless and devoted, but did not want him to die. The way they found to make him do that is to pretend he's about to sacrifice for the greater good, but stop him from doing it so he can still be in the next movie. Now we know 100% what drives him in part IX.
The scene loses that meaning if the idea is "Finn makes dumb decisions and Rose saved him from himself". This would have us going into IX assuming Finn will still need his hand held because he doesn't know when things will or won't work when everyone around him does. There's nothing satisfying or thematically relevant about Finn being saved from his own stupidity. I'm surprised people lean on this concept to defend this scene when it would actually make the scene even worse. I am giving the movie much deserved credit by pointing out that Finn could have succeeded
Thus, the audience has no reason visually, technically, narratively or thematically to believe Finn absolutely 100% wouldn't have succeeded. In fact, they have plenty of cues telling them the opposite, that Finn would've taken out the cannon.
It's just bad fucking film criticism that shows a startling lack of understanding and/or purposeful disingenuousness
It's not though. You can't blame the audience for everything. At a certain point, when a significant chunk of viewers are getting the wrong the idea, it's time to look at how the scene was shot and try to understand why a large chunk of the audience didn't see what you intended.
This is especially relevant when you are clearly going for a big climactic surprise. You can't bust out the angel choir, halo lights, and pensive Finn and intersperse it with cuts of forlorn Leia and company while they hear the canon is about to fire, and pretend "LOL Finn wouldn't have succeeded anyway" when you stop him
right before impact. Everything about that scene points to Finn being about to save his buds. The only way to subvert those expectations would've been to actually show Finn failing, which would've really made this scene dark comedy
