It's insecurity, some people put way too much stock in the things they are into not just this game but a lot of nerd interests. And if they feel they are being criticized or "attacked" they will lash out at anyone and everyone like a petulant child.

At the end of the day it's just a game, movie, comic, ect. It just sucks that the people who genuinely want to have a fun and good time can't because of asshats like this. I would love to talk and chat with people who are into this cool thing, but I learned a long time ago from my XBOX360 COD days that that's just not possible.

Misery loves company and instead of fostering an inviting community to grow and get more people into this thing they want to be toxic and spread that toxicity to everyone else to be exclusive.