You're correct up to a point. A statistical bell curve is present in most things. You'll have those who lurk, those who comment, those who post, and those that will moderate in any group. Make that group bigger and each category will grow too. The group can skew the results, lower the lurkers for instance, by making them answer questions before joining. They self select themselves as being more engaged.

But I agree, the current business models are big on numbers and not necessarily what is going on with those numbers. We've been taught quantity over quality in real world applications to our detriment. It's sad really.