It's the result of PR attacks and sadly they seem to be working.

Some of those writing are just parroting PR pitches and some just seem to depend on their limited experience with he service.

Also considering that the number of active users is but a fraction of the overall number of those who signed up (yet still a considerable amount) it's not fair to divide active minutes between all registered users. It might be a "ghost town" in comparison to Facebook but so is every other social service the tech blogs seem to be paddling, it's just that + is a bigger target for PR attacks.