That's not entirely true (your first point). Both my wife & I have met all sorts of acquaintances and what became good friends through interests that started w

That's not entirely true (your first point). Both my wife & I have met all sorts of acquaintances and what became good friends through interests that started with coincident physical locality: gyms, clubs, church, children's sports & school, etc. I don't think the problem exists completely in the way you seem to think. One potential mental block could be that spontaneity is a key piece of the equation. I argue that the vast majority of humans are not spontaneous and that's a hugely overrated attribute, if so. I 100% agree with your second statement, though, that the future of social networks will focus more on the social and less on the spam & social signaling.