@ThoughtBubble I have heard plenty of people say his has happened to them. It seems so common that I actually made an explicit rule against it -- "you don't have to play with anyone you don't want to play with, but don't try to convince other people not to play with them" or something like hat.
You have observed something important and quite relevant -- many, many MUers have the brain cooties. Some types of brain cooties get along well with other types of brain cooties but conflict harshly with still other types, and most of them make people idiosyncratically abrasive and idiosyncratically sensitive, so communities with high levels of endemic brain cooties get weird even without anybody being an actual asshole.