As a perfect example, the first thing I did when I got a smartphone was hook it up to Facebook. Then I discovered a thousand useless Facebook contacts had been downloaded into my address book. Finding people who I actually wanted to call or text became a nightmare.
I recently uninstalled Facebook from my phone because of the whole address book fiasco. I'm back to a simple list of contacts that I know personally - and it's great.
I'm probably just being a Luddite. I want an address book so I can quickly call Ted. Not so I can wade through all my Facebook, Twitter, Google+, LinkedIn, Foursquare, <Insert Social Service> friends while attempting to call Ted.