S/he means that the core problem in creating a "Facebook killer" is not creating a social network, but figuring out how to get users through it. Instagram, Snapchat, Pinterest etc did not use any new protocols or tech, but they were able to attract users and grow through their distribution methods (on mobile) and features (not their underlying tech). Using a new P2P protocol will not attract enough users to beat Facebook.
Nobody except Instagram, Snapchat, Pinterest, et cetera