For the record, the only person on this thread (afaik) actually affiliated with Matrix is me, and we categorically don't advertise but jump on discussions like this one to try to answer queries and dispel confusion & FUD.
The FAQ entry on XMPP needs to be updated, tbh - XMPP works fine on low bandwidth connections, and is typically lower bandwidth than Matrix (at least when using HTTP/1.1). The "not well designed for mobile use cases" was talking more about push notification support & history synchronisation, both of which XMPP has improved since.
The FAQ entry on XMPP needs to be updated, tbh - XMPP works fine on low bandwidth connections, and is typically lower bandwidth than Matrix (at least when using HTTP/1.1). The "not well designed for mobile use cases" was talking more about push notification support & history synchronisation, both of which XMPP has improved since.