Genuine question : do you think a privacy oriented social network where users pay a small annual fee (around $5) would work? Think Whatsapp (use phone number as an id, no native discovery, only connect through phone contacts, encrypted user data only to prevent database leaks from causing damage) + Facebook (feed like feature, share photos, videos, direct messaging, group messaging). No user tracking, no ads, just a…
People want to be able to find their friends, so you need some way for discovery to happen. If there's no tracking locations and relationships, then how do you do it? Usernames are the only privacy-concious way to accomplish that, and then you've just described MySpace. Facebook works because when you drunkenly befriend someone at a party, you can find them the next day online. It's bootstrapped discovery. Like it or not, that's what most of the world likes about Facebook.
Google almost solved this problem with G+, but they did it by scanning your email contacts. Is that still a privacy breach?