> Do we have any data to back up the claim that XMPP is no longer in
active use on the Internet?
All the data is contrary to the claim: https://xmpp.org/uses
XMPP is and continues to be widely deployed. I personally see it show up
in the telecom world fairly often.
Apparently Nintendo uses XMPP for their online gaming platform (
https://www.process-one.net/blog/ejabberd-nintendo-switch-npns/ )
What's lacking is a solid generic client for every platform with all the
features described in xep-0459.