alt Hacker NewsMost times I've seen complaints about it, it boils down to "XML being yucky" and the extension component model being difficult to write clients for, which is true but not really a fault of the protocol, it's more of an inherent tradeoff of supporting opt-in extensions at all
I don't have that many problems with XML myself, but XMPP is weird even in XML land, because it tries to do XML all the way.
For instance, it works as a constant, uninterrupted stream. You never close the document until the disconnection. Which means you absolutely have to parse it with a stream parser.
It could have been something sensible, like a document per message: "Here's 300 characters of XML document: <xml>....". But nope.
And what's up with this? https://xmpp.org/extensions/xep-0394.html