@izzy @hj Matrix's protocol is a nightmare because every chat is a blockchain (à la Git) which means that metadata for all messages, even messages that were deleted, are sent to every user who uses that chat, and every Homeserver involved in it, possibly forever. Plus it's HTTP-based.
In all, Matrx is much more cursed than XMPP's already-cursed XML-based protocol. All of this without mentioning Matrix's problematic state spy agency origins