I feel like every description of Google's chat application strategy ends with the punchline, "The Aristocrats!"

Yeah, it did. They handled it really bad. From my experience, back in the Google Talk days I could easily reach my family, friends and people at work via XMPP just because Gmail integration was excellent - no indoctrination required, they were already there checking their e-mails. Once Google forced the switch to Hangouts, it sadly became easier to reach them via Facebook. Nobody really cared to use Hangouts anymore, especially when people started to switch from PCs to smartphones where Hangouts weren't integrated into Gmail at all, and XMPP defederation meant that I didn't have any reason to stay there either.