But google invented Jingle, and in the XMPP space I can't imagine they didn't have a dominate authority. And you can add whatever extensions you want to XMPP, standard or not.
Basically all of the issues, perceived flaws or missing features attributed to XMPP in the old implementation of Hangouts were either misinformed or have seen development or new specifications in the XSF. Google never contributed to such discussions, with the exception of individual Googlers helping with Domain Name Associations (DNA, http://tools.ietf.org/html/draft-ietf-xmpp-dna-05).