federation with xmpp doesn't need to be configured. it is automatic. all you need to do is to send a message to someone on a different server. i am not on google, so i used this all the time to talk to people on google. until they stopped.

to get advanced features, google would have had to create a client that uses those features. much like they created the chrome browser.

i guess there just wasn't enough value in doing so. and there were to few people like me who communicated from the outside.