So the only point was in avoiding one time step like adding an account to the client (like users do with e-mail too) / or registering on some XMPP server? Still it hardly justifies creating more walled networks (unless they allow federation and regular XMPP communication with their servers).
To a degree they do, since users of one walled network can't communicate with users of other walled ones, and if they want they need to create an account in each of them. While federated XMPP is like e-mail, i.e you can use one ID to communicate with users from many servers. So there is an obvious comfort even for the end user.
