It’s an unpopular opinion but I completely agree. I’ve tried Matrix, not only could I not get more than 2% of my community to try it, but it’s horribly unintuitive and limited for server owners. Shut it down after a few months.
I have a rocket chat server going now, some similar issues, but at least it has more control than Matrix. Still only a fraction of my Discord and Telegram user base has joined, but it’s similar enough that people are at least willing to try.
FOSS alone is not enough, the wider public doesn’t care, they just want something easy and convenient.