XMPP has been abandoned and considered hostile. At one point it was good, but nowadays it suffers from many issues regarding Freedom. It is said that XMPP is decentralized, but i would argue that is is psuedo-centralized. When a group of users can block any user or entire server from every relevant server on the network at their own will because people blindly trust certain extensions, obviously some power-tripping people are going to start problems. I would actually consider this an attempt to have control over the entire network and only allow things they approve of, based on my own experience with the RTBL (and MUC/Server lists, but this is a whole different topic to get into). Outside of this, its never been a secret that XMPP software sucks, and XMPP itself is designed horribly, overengineered, and various aspects could be considered insane. At this point its recommended that users switch to sane alternatives like IRC.

Read Technical Problems with XMPP. (External)