Actually, I agree with you on the benefits from social media to the society. But for 5% of useful features, there is 95% of trendy/fashionable projects that do not have any benefits to the grand scheme of things, are really expensive (color?) and are driving workforce away from more important projects.
You're conflating useful with productive. Huge productive industries employing tons of people are built around things that are merely trendy and fashionable (pop music, LV purses, etc).
