I was also there. G+ was born into an environment of fear. Google leadership had convinced themselves that Facebook would dominate tech forever in every product

I was also there. G+ was born into an environment of fear. Google leadership had convinced themselves that Facebook would dominate tech forever in every product area because all you had to do to make something successful was make it social, and boom, it won. They were over-generalising from Facebook's success in photo hosting vs Picasa, as well as a few other products. The big fear was that Facebook would do email and it'd not be as good as Gmail but everyone would use it because it was social, that Facebook could even do maps or web search, same thing. So G+ became seen as a "save the company" hail mary move. After some years passed Facebook rapidly reached middle age, their attempt at email sort of flopped, they didn't launch dozens of new products and the ones they did launch didn't replicate their earlier success, and the fear ebbed away. Meanwhile the G+ product managers (mostly Vic Gundotra) had burned a lot of bridges by forcing G+ into everything. Whilst Larry/Sergey/Eric were afraid of Facebook he had absolute power because they felt only G+ could save the firm. When it became clear that was an over-reaction he lost his protection and was out.