xmpp is not "one standard" it's an extensible mess and no two people use the same client/server combination, leading to some kind of factorial explosion of mutually incompatible software. there are over five hundred XEPs and any given project has a unique view of which ones are "necessary" and which are "supported" and which are "deprecated" and which ones you should go to jail for even reading.xmpp has xeps for systems administration, internet of things shit, service discovery, and a million other things that should never have been shoved into a chat protocol, while the xeps that are intended to fix the actual issues that affect users are "deferred" because it's a hell of a lot easier to invent an entire new use case for xmpp than it is to fix any problems with existing xeps.this, combined with the excessively verbose markup, means that starting from scratch has two incredibly attractive benefits: one, you don't have to learn this tremendous bureaucratic protocol maze, and two, just about any wire format you can think of is going to perform better than xmpp over slow or intermittent network connections, which are the majority of internet connections.