I read this as a trivial 'truth' that I've internalized myself as well; but the way you worded it... makes me naively ask:
doesn't it speak to the limitations or choices of XMPP itself then, not the idea of a common protocol, if businesses can't reliably extend the protocol (only custom fork, and somehow barring eventual upstream contrib, whatever)?
I can think of an extensible protocol paradigm, with 'extensions' (really just libraries, packages, like those we fetch with `apt` or `npm` and optionally push to clients as well). Down to first principles, that's how we structured UNIX/Linux, most modern programming languages, the web itself (well, at least the Js and now wasm part of it).
I actually don't think it has anything to do with technology or problems with XMPP. Corporations can move standards better than anyone (look at web and chrome/google). If Google and Facebook had scale problems then they would just build better implementation.
Facebook messages happened when FB didn't have so many users and in chat space there were XMPP services like ICQ/Jabber. Network effect was against FB so it made lot of sense to federate. When FB was convinced that by killing federation more people come to FB instead of leaving they just pulled the plug.
I am sure that if 80% of email users were using gmail Google would do the same thing. There is a chance of that happening... First gmail adds some amazing but nonstandard features, people start relying on those features and in time gmail becomes the one. Only thing thats keeping that from happening is actually other big businesses.
doesn't it speak to the limitations or choices of XMPP itself then, not the idea of a common protocol, if businesses can't reliably extend the protocol (only custom fork, and somehow barring eventual upstream contrib, whatever)?
I can think of an extensible protocol paradigm, with 'extensions' (really just libraries, packages, like those we fetch with `apt` or `npm` and optionally push to clients as well). Down to first principles, that's how we structured UNIX/Linux, most modern programming languages, the web itself (well, at least the Js and now wasm part of it).
(Thinking out loud...)