We're focused on one main thought: you don't, by default, socialize with all your friends plus "acquaintances" at once. Just impossible. When you're with your family you socialize in the context of family. You don't talk about the crazy party last Saturday with your family. This is the idea we focus on.
People return to FB because of inertia basically, not necessarily because they need to. That's why they start to whine and mainstream media have been reflecting this situation.