I may live in a nerd specific environment but gchat was our goto product for a long while. We had our notifications build in trough XMPP just like people do with slack now. Some of us used their own XMPP servers, and pretty much everyone was reachable trough it beeing google and everybody having a gmail and/or android phone at least. There were also several cool mobile and web apps that worked very well for XMPP, though not with high load thats true.

When you removed XMPP and forced to hangout it died off pretty fast, no API and the Hangout thingy was not even working on Linux (not sure if it does these days, i never tried).

I see your points, but i cant stop to think about this as the probably most evil step google did to my workflow.

Edit:// I use hangout now to transport links from phone to desktop and the other way around. It totally lost its purpose :/