Oddbean new post about login | logout I know but it seems people here do not share telephon numbers at all with someone they just might be able to trade with in future. Only when they know each other well.
that is a feature. you don't need many people. Vexl does extended social graph (friend of a friend) and it's good if both can verify with someone they don't know. Social networks expand really fast, no need to worry about it. it just needs a little push and then it goes well