But is it easier to 'drift apart' from people you know if you're the only one they need to remember specifically call or send email to, when they can in general assume that all their friends sort of follow their FB updates? But it's awkward if you're the only one who keeps contacting them.

If you have already hard time building very durable friendships and are sort of hang-around member of your social circles, the social media -- if you refuse to use it -- does not exactly make your life easier.