I think you are overdramatizing Facebook's importance quite a little bit here. It's not like your friends will hate you when you quit and I have seen plenty of people quit online social networks while retaining their life just fine.

I could make up a similar argument the other way around: to me, services like Facebook provide little to no value; I can quit them just fine. I have communication details of a lifetime in Google, I store my documents with them, organize my calendar. (Note: I have heard Google's export features are quite okayish so that argument does not really hold.)