Matrix is way more expensdve to run by its protocol design

Eh, I've used both a lot and matrix is kinda flailing from my perspective. At least for casual use. If you are a client of Element maybe the experience is better, but with their "next-gen" battery friendly client they've been working on for years, I can't even get notifications working through public unified push servers when using matrix.org. Meaning that just to get started using it I have to run my own matrix or up server.

i remember that too. XMPP is still alive and kicking, just a lot quieter these days. :)