I'm sorry but social proof is ridiculous. It's not a fair system. It can be manipulated. What if someone has no friends, and they like it that way? Also, most people are not honest. Using feedback on a service is great, but on an individual is scary. Why? Have you tried to sell on eBay ever?
People for money can leave any positive feedback. So the trust system between friends does not work. In any project where there is something other than proof of ownership or proof of strength there will be no success. Although it will and show something interesting, but I definitely will not invest in such an idea.