@freemor@identi.ca though I generally agree, in this particular case (briar) is interesting as it appears meant to synchronize directly between devices using bluetooth, wifi, or tor. That's something that doesn't really align with traditional XMPP. It claims it will be Free Software when it's out of private beta.
So, I'm reserving judgment until that happens. I would hope that if the experiment is successful then a full RFC standardization process would occur, with multiple implementations.