"Denshi explains the basics of XMPP: The future of decentralized messaging." > finally someone that actually understands what they're saying. Matrix is questionable open-source and privacy disaster, XMPP is tested, reliable, secure and above all a truly open standard and decentralized it just lacks some investment in better mobile clients.
What people fail to see is that XMPP is the only solution that treats messaging and video like email: just provide an address and the servers and clients will cooperate with each other in order to maintain a conversation. Everything else is just an attempt at yet another vendor lock-in.