TPTB, using a social network doesn't equate to "working". You are miscorrelating the two. You are correct in the fact that people share for much more valuable reason than ad revenue. That fact leads me to ask, "Wouldn't you rather use a social network which rewarded you for your participation instead of a centralized entity?"
I am not "miscorrelating" any thing here. Earning miniscule revenue for sharing isn't a compelling feature.
I think you are underestimating the compellingness of that feature. People on social networks constantly "share, like, pin" things, events, artists, etc with their friends. Who wouldn't prefer to earn revenue for their activity, regardless of how minuscule, instead of it going towards a centralized corporation like Facebook or Twitter? Eventually over time, I imagine that it will add up to more than you think.
I haven't seen any compelling feature or niche articulated for Synereo. I've read a 50+ page Synereo white paper of technobabble about process calculi.
You don't think that at the very least being free to speak your mind without Facebook / Twitter censors is a compelling feature?