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Mastodon's official stance on Threads
(blog.joinmastodon.org)
This is a most excellent place for technology news and articles.
Google Talk was using XMPP from 2006-2013. Facebook Chat was using XMPP from 2010-2014.
It was these two services that killed all the prior messaging apps (and eventually XMPP too), and I was referring to the before-times.