People love hating on stuff.

I don't hate Matrix but I'm not a fan. My only experience was on mid-size chatrooms where that was enough to notice the usual e2e UX issues just amplified by the number of users. I also remember reading articles about security issues. Both of those things make me reluctant to use it.

At the same time, I don't have a serious alternative to propose for multi-chatroom e2e messaging software (I haven't been looking though).