it's not entirely bullshit.
they forced g+ on every youtube commenter to drive up the usage statistics. I'm "active" on google plus and I know plenty of other "active" people too, while in reality we're just continuing to use youtube as we used before g+. and that's majority of g+ use. so if you take that out what you're left with is peanuts, almost everyone with a google+ account doesn't do anything non-youtube related with the google+ account and this is accurate! fuck, I would say that 1.5 billion of those users don't even fucking know they have a google+ account!
this is result of google being very active in tricking people, and shoving g+ on them through repeated popups, clickhere's, accept this new term and you'll be on g+, etc etc bullshit. and by repeated I mean wording it differently every time, not including a "don't fucking ask me to join g+ again" and so forth. if you were an active gmail user then sooner or later you were going to slip up and join even if you didn't want to - and if you wanted to comment on youtube you simply had no choice, and if you thought you had then you got tricked by some updated terms checkbox, and BOOM suddenly your profile pic was a on a public google+ site and you were a google+ user in statistics.
(and most g+ content isn't private, unless you count g+ chats as "content", which you really shouldn't, this really is the difference to facebook - which makes google+ just a big collection of blogs/self advertisements)