Facebook sure adds value. It connects people. Friendships, marriages, partnerships, businesses, and more exist because of facebook. I am not a user but the value it provides is real. Otherwise people would not use it (Google+).
Maybe the fact that reality is clearly contradicting your intuition about value is important? 1 Billion-ish people find Facebook valuable. You disagreeing with them just makes you wrong, or maybe lacking in empathy. I didn't understand the value in ridesharing. I still think it shouldn't be nearly as popular as it is. But that's me not understanding reality; it isn't reality being wrong.