Earlier quoted context omitted.
Google shut down XMPP support because none of the other large vendors were playing along. Because of how XMPP federation work, Microsoft could reach out to Google for presence and other information about friends, but didn't need to return the favor (they were doing one way federation). So it allowed for a "better" experience using other companies XMPP networks. Edit: Source for my beliefs on the above: http://www.ucs…
Facebook did provide XMPP service until the same time that Google ended it. So that’s definitely a wrong statement.
They never supported federation.