And people shouldn't necessarily expect that they can hold a full veto over the game, beyond simply walking away from the game,. But, in this thread, you can find people arguing that if someone was made to walk away from the game, because the group couldn't accommodate them, that that was a monstrous act. Maybe in some imaginary cases it was, but not for the majority that actually come up.
Been reading the thread from the beginning and I think this tidbit gets to the heart of things.
What is more important to you? The game or the people at the table playing that game? Because that's what it boils down to. "Oh, I can't change my game" means that the game is more important than that person. That doesn't make you a monster, but, it does show where your priorities are. If changing your game provokes that much of a reaction, then, sure, that player probably shouldn't sit at that table since that table obviously isn't interested in respecting that person's boundaries.
Again, this isn't a bad thing. We're playing a game. I should not feel like I have to deal with someone else's baggage in my free time. I'm not a psychiatrist. I'm not a mental health care worker. I'm sympathetic, sure, but, by the same token, I shouldn't feel like I have to deal with someone's issues in my free time.
OTOH, if you approach the hobby from the perspective that the people at the table are more important than the game, then, well, it would make perfect sense to change the game to accommodate someone's issues.
So, that's where it really boils down to. What's more important to you. And, obviously, that can change over time and situation as well. A con game with strangers is a different situation than a home game that's been running for extended periods of time. This is something everyone has to think about for themselves.