I definitely agree with this sentiment. I work at a technology-focused software startup, and while we all have Google Plus accounts, it isn't a service that most of us use regularly. Given the fact that I've never even been "added to a circle" by someone who isn't part of a technology-focused university or company, it seems less likely that there are legitimate and massive (400M!) pockets of users floating around anywhere remotely close to my circle of acquaintances.
That said, I'm on the US East Coast, so I could easily have a biased viewpoint. Perhaps all the Google+ users are elsewhere in the world? Or perhaps the little Google+ notification bar at the top-right of the default Gmail interface counts as an impression for the purposes of this study?
That said, I'm on the US East Coast, so I could easily have a biased viewpoint. Perhaps all the Google+ users are elsewhere in the world? Or perhaps the little Google+ notification bar at the top-right of the default Gmail interface counts as an impression for the purposes of this study?