Read this first:
We decided it’s time to fix this, not only in YouTube, but across a user’s entire experience at Google. We want to formally retire the notion that a Google+ membership is required for anything at Google… other than using Google+ itself.
Then read this from 2011: Google+ needs to work for Larry Page’s sake
Then also read this for 2011: Larry Page Just Tied ALL Employees’ Bonuses To The Success Of Google’s Social Strategy
Good to have some historical context.