Sure, but they're a tiny fraction of the mainstream users and you can already have that sort of experience with blogging and microblogging. Relevant social netw

Sure, but they're a tiny fraction of the mainstream users and you can already have that sort of experience with blogging and microblogging. Relevant social networks as the public knows them are hard to develop local-first. Even the humble forum where strangers meet to discuss is really hard to do that way. If it needs centralized moderation, or a relevance system via karma / votes, it's hard.