IIRC they were pretty up-front about why they dropped XMPP - most of the clients connecting over XMPP were spammers, and there were few enough legitimate users

IIRC they were pretty up-front about why they dropped XMPP - most of the clients connecting over XMPP were spammers, and there were few enough legitimate users connecting over third-party clients that it made more sense to drop XMPP support than build spam-blocking solutions.