On the Google side the XMPP federation got killed when Google Hangouts and Google+ became the core strategy. The company wanted to focus on "social" (but their own social network) and didn't care about other chat. Back then I worked on the App Engine team which had a XMPP Chat API. When GChat killed XMPP Federation that API lost the majority of target users as a result. I tried to make the case for maintaining XMPP support - taking it up with some VP of Engineering. Alas, nobody cared about the opinion of this random guy in developer support (~2012, early days of Google Cloud)