You forget that Google was worried about other XMPP services stealing user data. If I remember right, some services (maybe it was FB) was not sending out all da

You forget that Google was worried about other XMPP services stealing user data. If I remember right, some services (maybe it was FB) was not sending out all data to Google in the federation system (I forget if it was names or friends lists or something). So it would allow other services to ingest data Google was sharing, but the sharing wasn't reciprocal.