Last time they touched an open chat protocol, they hung it out to dry. That was XMPP. That’s why more than half of the fediverse is reluctant or outright hostile to federate with anything meta.
XMPP is used in many, many places. It’s just not usually explicitly known that the backend is using that protocol
maybe they could convince meta to use it
I think he/she meant convincing Meta to use MLS, not Matrix.