XMPP didn't fail. It's used everywhere. I can look at my firewall traffic any time and I always see XMPP traffic from the various Big Tech companies you already

XMPP didn't fail. It's used everywhere. I can look at my firewall traffic any time and I always see XMPP traffic from the various Big Tech companies you already know. But, like commenter tetraca mentioned, XMPP has been embraced and extended, and it's not very interoperable, as implemented. SMTP has been and will always be around forever, albeit eventually viewed like FAX is today. I personally view it like that today.