A good social network should be easy and accessible from anywhere on any device.
It's the reason that people love FaceBook, Twitter, and Instagram. Quick and easy signup, nothing technical or complicated, and then they can access it from wherever they are on whatever device they have to hand.
It's also the reason that I'm here posting on Cake after trying out about 15 different 'alternative' social networks during the last week for an article I'm writing and dismissing most of them incredibly quickly.
People care about privacy but they don't all want the complication of something like Disapora, they have to start selecting nodes, etc. and just drop out before they even get signed up.