I think XMPP is just plain better than Matrix. It does all the same things but with significantly less processing. You’re not copying data between servers, so less RAM is needed and you have less worry about one of your users accessing someing illegal on a different server because you’re not caching it.
I want to love Matrix, but every time I use it I think about whether I could just convince more people to use XMPP instead
I think XMPP is just plain better than Matrix. It does all the same things but with significantly less processing. You’re not copying data between servers, so less RAM is needed and you have less worry about one of your users accessing someing illegal on a different server because you’re not caching it.