I'm willing to bet that your friends and family wouldn't be happy if the European Union would mandate using IRC everywhere. Heck, why not go further and stick to the good old ntalk [1].
I used XMPP around 2003 when it was still called Jabber. I can't say there's something major wrong with it (only XML verbosity comes to my head), it's just the idea of making it mandatory. By the way how come some EU officials use Zoom? [1] Where are those good open standards?
Funny you should mention Zoom, which just like Whatsapp is pretty much a half-baked proprietary XMPP implementation. Now if we had proper interop regulations mandating interoperability between commercial entities (no need to apply that to hobby/research projects), we could talk between all these networks.
Sure it would take a few months of serious dedication for these chat vendors to write specifications for the protocol spaghetti they came up with, but the benefits would be tremendous.
So why is "nobody" using XMPP protocol? The problem is not exactly with the specifications (although there's still a little margin for interpretation here and there, they keep evolving for the better) but rather with the implementations. Since a protocol is not tied to a single implementation, it requires additional resources to develop user-friendly clients. This fact is used by an argument by some people (see also: m0xie's The Ecosystem is moving) to justify centralizing all communications and protocol development. This argument was amply debunked by Daniel Gultsche (who maintains an Android XMPP client) and Drew Devault (who maintains an (unfederated-so-far) forge):
There's also a lot to say about the Matrix/Element approach, which has some good and bad sides. I'm happy to elaborate if that's of interest to someone.
If you want to have provider choice for customers and interoperability between messaging apps, I don't think there is another way than making standards mandatory.
Why do you think WhatsApp reached a billion dollar evaluation? Not because users have the freedom to move to a different provider and still be able to talk to all their friends...
The only other possibility is that users start rejecting providers who do not comply with internet standards (and I don't see that happening, even here on Hacker News).
Making something mandatory will definitely push things forward because what else are the providers going to do? Though I still have doubts about real progress being made. EU can't can even add VP9 and AV1 to the list of codecs used for Digital Video Broadcasting (DVB).
Instead maybe the government should start eating its own dog food and use an open standard for both internal and external use.
WhatsApp is basically an unfederated XMPP provider.