Part of it is me already hating replacements since surprise, people are different
I don't think there are any specific problems regarding typical mafia rules, but I do think it can cause unnecessary confusion
I dunno if I can like post here or w/e but I really don't like the idea of previously dead players replacing. What I might be able to do is outsource to a couple other forums I play on to find replacements. Lemme know if that's what you want and where I should direct them