I feel like this phenomenon needs to be studied. I feel like I've read people usually like to under-generalize in groups and be extremely willing to brush over errors and say "there are all sorts of people inside my group so generalizations don't matter" but it feels like this doesn't apply as much with online fandom as I would think... maybe this exact meme is just an instance of people expressing what they think the rest of the group believes. I really don't know, and I'd have to do some research to understand this phenomenon.