This is the exact reason that I ignore any article or blog post announcing that the author has quit Facebook, Twitter, Foursquare or any other social service. If you're quitting you're not seeing the benefits. The people who continue to use the services are reaping the benefits.
My take is if you have a way to announce to people that you are quitting social_network_001 then you likely didn't need it and aren't even close to an average user anyways. It's when your average user stops or worse slowly stops using your service that should set off the alarms.
