@thomas What exactly is not nice about XML? As I said, I've heard this objection, but I want to understand it.
I don't think extensibility is a problem at all. Certainly building a client for XMPP with extensions is as easy as building a client for a protocol with those extensions builtin. Have this "mess" of extensions means we have a lot of under-featured clients + a few fully compliant ones instead of just a few reference clients like Matrix has.
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