Your perspective on "empty calories" social engagement is very narrow in my opinion, because you seem to equate all social interactions by the measure of existing, objectively bad, services. I think that over time the rise of small indie servers that will work on a social graph but in a similar way to email, will prove that "meaningful" social networks can exist, and my personal hope is that they won't be focusing on monetization. I don't see any reason why companies won't be able to build on that and offer you the same guarantees about your data that your email company gives you.