If you read the XMPP discussion from the other day, one of the points highlighted was that there's no common spec for modern features so it's really hard to kno

If you read the XMPP discussion from the other day, one of the points highlighted was that there's no common spec for modern features so it's really hard to know if a given client<->server combo supports newer features. IRCv3 is the same idea. Some of it is stuff that's been around for ages so clients just assume it's there like SASL and capability negotiation - these are much more specifying what servers/clients already do, IRCv3 is not adding to complexity here because the complexity already exists. The second is more green field projects, like the stuff to allow a more web client friendly protocol compared to IRC currently by defining how to use web sockets avoiding the need for stuff like IRCCloud or Mibbit proxying their user's connections. Or chathistory to make it more mobile/not permanently attached friendly.