Comparing Matrix with XMPP is flawed
Jabber (later XMPP) started 1999. Matrix started 2014.
XMPP superseded fundamental RFCs (client to server RFC and server to server RFC). XMPP has at least three different/competing XEP for end to end encrypted messages. XMPP has at least two competing XEP for file transfer. XMPP has competing XEP for audio/video "calls". Have fun building compatible clients, servers and ecosystems.
If the initial Matrix devs are clever they learned from the XMPP problems.