I understand. But that's not what we are really talking about here. I was hoping that the post prior to this made it clear.
Look, if someone is saying, "I can't stand hit points. They are breaking my immersion!" Then maybe that is right. Or maybe, they are complaining about something (as people tend to do on the internet) that they can, in fact, deal with and/or house rule around pretty easily. It's the nature of the game.
That's why I made the analogy to suspension of disbelief and fiction. Of course all fiction (books, movies) requires the suspension of disbelief. That the "buy in" that you "volunteer" when you engage with it. If someone says, "I don't like Buffy the Vampire Slayer" because "vampires aren't real," then, well, I mean, okay. They never engaged in the buy in, yada yada yada.
Where I think you're not understanding what I am saying is that in TTRPGs or in fiction, there can be things that are intrinsic to the material that, usually for idiosyncratic reasons, break someone out of the fiction / immersion, and that's NOT part of the initial buy-in.
For example, let's say someone goes to see a science fiction movie. Now, maybe there are numerous things that they accept that don't bother them, for whatever reason (like, oh, sounds in space to start with because space battles are cool). But then there's one scene where something happens and suddenly, for that person, the suspension of disbelief is lifted. That person "bought in" but there was something intrinsic that broke them out of it.
And you know, if this has happened to you, that you just don't ... re-immerse yourself. Sure, it doesn't mean that you storm out of the theater (or quit the TTRPG), but you also can't say, "Look, it's all just fiction, man. Get over it. Suck it up, buttercup."