Facebook for me is much more enforced. A lot of mom&pop stores publish their opening hours on facebook only. Clubs communicate with their members via facebook, so you can't subscribe to the yearly bbq etc without it. Small local sales, events,.... All small things, but death by a thoudand papercuts.

I held out on facebook since last year, but have given in. My wife is my only friend, even if facebook is pushing a never ending desperate barrage of youmightknow mails.