

Most of the modern clients agree on the core set and thus interoperate fine for most normal things.
So you think it is a sane solution to mark essential features as optional extensions and then have a wink-wink, nudge-nudge agreement of which of these “optional” extensions are actually mandatory? Instead of having essential features be part of the core protocol?
But more importantly, XMPP sucks because it does not have one back-end implementation like Vodozemac for Matrix. So let alone being unable to have security audits, you are forcing client developers to roll their own implementation of the e2ee, with likely little to no experience with cyber-security, and just hoping they will make no mistakes. You know, implementing encryption that even experts have hard time getting right.
Well, yes. I just did not consider them to be the ones discriminating if it is against the law, but the government.