I see a lot of rationalization here about why Google+ didn't take off, related to feature set, Facebook, etc.
Let me throw wood on fire ... the reason Google+ is a failure has nothing to do with any of its features:
1. they killed Google Reader for it, which was more successful than Google+ ever hoped to be, forever tarnishing Google's reputation
2. they had the Real Name Policy ... by the time they reversed and apologized for it, the damage was already done
3. they shoved Google+ down on everybody's throats, like YouTube users, exposing their real identities in the process
There are no other reasons that matter. Google+ could have been at least at Twitter's scale. Twitter still understands their audience, but Google never did.
Let me throw wood on fire ... the reason Google+ is a failure has nothing to do with any of its features:
1. they killed Google Reader for it, which was more successful than Google+ ever hoped to be, forever tarnishing Google's reputation
2. they had the Real Name Policy ... by the time they reversed and apologized for it, the damage was already done
3. they shoved Google+ down on everybody's throats, like YouTube users, exposing their real identities in the process
There are no other reasons that matter. Google+ could have been at least at Twitter's scale. Twitter still understands their audience, but Google never did.