Once again, I never claimed that it overrode the main premise. I said it stood alongside it as a core aspect of the series; I even clarified that yes, it is not the main premise of the series. If you'd like continue to assert otherwise, please directly quote where you're getting that from and I'll explain to you why you're wrong.
None of anything else you are saying really detracts from my point. In fact, some of it actively supports that rape is a core aspect of the series as a result of being a world building plot point. Rape is not merely referenced through the series, it is not just alluded to. It is built into and underlies every part of it. It is a primary motivation for goblin attacks on humans, why they are so aggressive and the main tool the work uses to show their brutality and lack of sympathy. Goblins exist to be killed, and the main motivation the work gives us readers (not necessarily the characters, mind you) is because of the horrible sexual violence they use against women. The few times we see goblins exhibit any other emotion than murderous anger is while the process of attempted rape, and even the goblin bosses frame rape as a threat, or as part of their history (one goblin actually blames women's emotional weakness for how he was able to survive for so long, as he is picturing himself raping them). When Goblin Slayer, at least the manga, needs to remind us how "dire" the situation is or how terrible the goblins are, it uses rape or the threat of rape against a character to communicate just how bad things are. And it reminds the reader constantly, with framing that juxtaposes terribly with how leery it is in comparison to how it shows murderous violence and always uses young female characters. It's part of the Priestess' starting trauma, and the aspect of her trauma that she most interacts with as a result of her own attempted assault, what she witnesses before Goblin Slayer enters the stage, and what she finds once they rescue the fighter girl. Another major character is centrally defined by her experiences with goblins, and while this could in another way be an interesting look at how powerful characters can live with and move past their trauma, I can't say that it works like that here. Every other female character at the very least must live under the specter of rape as a result of the narrative being so intertwined with rape as a primary motivator for the goblins.
It isn't just keeping a worldbuilding plot relevant, it is both in the background and the foreground of Goblin Slayer, and it is most certainly an actual focus of the visual narrative. Sexual violence is the visual narrative of why we should hate the goblins. None of this is me reaching, this isn't something that is subtle. If rape is part of your central narrative, is a relevant part/threat of every single female character's history in the past or going forward, is the way goblins attempt to assert their dominance over human beings and their reason for aggression (which in turn undercuts every character's motivations against them), and is the main method used to reinforce the dark nature of the world, then I can't even begin to imagine how you could assert that it isn't a core aspect of your series.
The creators wanted a way to engender harsh feelings from their reader while simultaneously reinforcing how dark the world is. They not only chose rape to be the primary way to accomplish this, but also they chose to depict it in the manner and frequency they did. Once again, there is another work out there with a similar starting premise that manages to not have rape end up as a defining aspect of the series that it will go constantly go back to. There are other ways of giving the characters primary motivation without constantly falling back on rape shots with gratuitous framing, and I won't laud Goblin Slayer for constantly going with one.
It doesn't have to be a "rape-focused work" to feature rape as a central aspect of the story. That would make it a hentai. What it does do is intertwine rape so much with the central narrative that it disproportionately distorts so many other aspects of the series to ultimately lead to it. Which the creators did not have to do. They chose to force this centrality.
Rape is a major part of Goblin Slayer's central narrative, is it's emotional crutch, and is a major part of character development (or lack thereof). I assert again: It is a core aspect of the series.
