<quote>FB is a classic example of a network effect. leaving it for greener pastures would mean being on a scarcely populated social network.</quote>
Would that be such a bad thing? How many of peoples connections on social media are genuinely friends and how many are passing acquaintances they haven't spoken to in years? I accept that getting rid of Facebook would be a challenge for a lot of people, especially since they got their claws in to so many sites as a logon provider.
I was very briefly on Bebo when the social network explosion started, never saw the appeal and deleted my profile. I am now in a situation where Facebook very probably knows a lot about me via people I know, but as I've never had an account I can't ask them to show me what they have (not that they would anyway)