[saurik]

But that isn't really use the case for a typical social network. Most people I know post the vast majority of their posts as "friends only", and even those that make public posts usually limit comments to friends only. The only form of communication that should be allowed by non-friends is "friend request", and really: once you've been using a strong social network for any period of time, you can turn on "only allow friend requests from friends of friends" without much consequence (of course, it will take a new network time for that to be viable).