Addons and XIV are in a weird spot. I'm a pretty unapologetic tyrant when it comes to tool assists in prog (and, seriously, stuff like zoom hacks or anything that puts input into the game for you which are unabashed cheating can fuck right off), but there are combinations of events that have made tool assists varying levels of semi-expected and it gets to be a super grey area.
Nael's RP lines in UCoB is probably the gold standard for tool assisted mechanics--the original lines were designed, in Japanese, to have clear tells in text for what the mechanics were. Each mechanic was, IIRC, telegraphed with specific characters and was printed on its own line with the mechanic at the... front or end of the line, I. forget. In an attempt at ~QUALITY LOCALIZATION~ this clarity was absolutely destroyed in the English translation, with various wording in different phrases, and things on a single line. No clear break, no consistent indicator, and it increased the amount of memorization and reading required. It introduced artificial difficulty into the fight that wasn't intended by the original designer--you were meant to have to learn clear tells that were muddled in localization. I believe this was actually finally addressed in Shadowbringers, with Nael's RP and its formatting being corrected, but it was one of the first times I sucked it up and installed triggers for a mechanic. It didn't feel great, but I didn't feel like doing challenge mode because the English translation decided to sacrifice fight design for flowery prose. Without ACT triggers, they probably would have fixed the fight implementation sooner, but with them the artificial difficulty was removable until they did finally get around to addressing it.
I tend to contrast this with the UwU example--where people would program Triggernometry to call out and/or auto mark where people should place Titan gaol--because this was a mechanic meant to intentionally be rushed coordination and intentionally not super-obviously telegraphed. It was supposed to be hectic and reward teamwork, it was the same difficulty level for everyone doing the fight, and offloading the actual thinking part to a plugin felt wrong to me. I refused to consider triggers and shouted down people I raided with who wanted to use them. This was not the common route people took with the mechanic, but I wouldn't have felt right clearing without us being able to handle priority ourselves.
And then you get into things like Anatman. The short version is: Anatman is bullshit garbage and everyone involved in its current implementation should feel bad; the long version is that a 'proper' Anatman opener literally relies on the tank pulling at a specific time with relation to server ticks. This is incredibly stupid. It also means if your monk is trying to do really well at a fight, either somebody is installing the stupid Anatman timer plugin so the pull is synced properly, or you're ruining some of your monk's pulls because Anatman is a garbage mechanic and the server tick comes late. The existence of the tick timer plugin makes it somewhat controllable, which probably puts a lid on some of the monk complaining, so maybe without plugins there'd be more pressure to fix that, too. But in the end we accept the existence of the stupid plugin and do countdowns in multiples of 3.
I dunno--I used to make my own timelines to help me with mid-fight planning during farm/optimization runs. It took forever. Now, once we're out of prog, I update Cactbot and they're all sitting there and I don't have to spend fifty years picking through fflogs and figuring out the best sync points. I'm still a nightmare to deal with when it comes to anything I consider cheating--at this point nobody even seriously suggested the Titan plate-punch triggers because it wouldn't have gone well--but when trying to plan CD usages having the timeline handy is nice, and when revisiting a fight after an extended period of not running it (or venturing into parts of a fight you haven't seen it survive to in a while),a timeline is a convenient way to not sandbag.
Everyone basically has to develop their own standards and find people to raid with that either have the same or will put up with them; I'm all for the devs coming up with ways to break Cactbot and timelines if they can, but at this point I've more or less adjusted to using it for the timeline and ignoring the warning text 90% of the time (finding out that it cheated the lasers in O12S while watching somebody cheat on their stream was hilarious, since I'd apparently been ignoring it for months at that point.)