Matrix advertises themselves as an eventually consistent global JSON DB. So it makes sense anyone can build a client and stuff something in there and maybe only their client really handles it.

Seems like a better idea given the failure of XMPP. XMPP was a communications protocol lots of products used like Google Talk, but got dumped when they wanted to do their own proprietary stuff. It feels like Matrix will be less likely to get dumped like that since they are just a general purpose global DB.