The question would actually be why XMPP multi user conferences (MUC) are not in the running. Regular XMPP is one on one. XMPP has archives and carbons now and

The question would actually be why XMPP multi user conferences (MUC) are not in the running. Regular XMPP is one on one. XMPP has archives and carbons now and in theory they work with MUCs. Dunno about the practice. A recent article suggested that the ability to edit and delete old messages is essential. Pretty sure a MUC would not let you do that. I am personally not all that concerned about this particular feature.