Atleast 50% of my friends don't really get into the social networking. Either not having accounts or checking it once a week/month. I would say 95% of the people I now have email addresses and I can communicate with them.
When ever I see stats its always x amount of people use this per month. And I thinks for the same reason that exists in my friends. They don't care to much for that much about these sites.
I would guess over 90% of the content on FB is from 10% of my friends. The rest aren't so excited about it. So far none of my friends are really using Google+, and the ones that are I could say less about the content they are posting.
So I think you are misguided, and are under estimating how little interest a business is going to have towards storing there business data on what for many (including several of my own products) is a competitors system.