A trend I've noticed is that the value of my average social connection on networks where the connections are symmetric -- i.e., bidirectional, like friendships on Facebook -- tends to go down over time. That's because as sites grow and become more popular, a more varied assortment of people friend you. And there's a social pressure to accept these requests, particularly when you have some real-world connection with the person.

Six years ago my Facebook friends were primarily my real friends. Not all my real friends were on Facebook, but nearly all my Facebook friends were real. Today, I'm "friends" with plenty of people I've never met nor even had much communication with. Two years ago all my friends on Foursquare were people I was genuinely happy bumping into on the street (and thus sharing my location with). Today, that's not the case.

What's interesting is that this isn't a problem on asymmetric networks, like Twitter or Instagram. The average value of a person I follow on Twitter has if anything gone up in the last four years (I have no idea if that's true of my followers, but the great thing is it doesn't matter). My following someone on Twitter is a true assessment of whether I care about what they're saying. My being connected with someone on Facebook or LinkedIn carries no such significance.

I don't think the answer is just that I should be more discerning about whom I accept. That works to a degree, but when the predominant social norm is that the connections are cheap (as is the case with Facebook), it gets harder and harder to decline people's requests. It's even tougher on Foursquare, where you can have people you know quite well whom you simply don't want to share your location with.

The network that figures out how to scale into the mainstream without sacrificing the value of its symmetric connections is going to be insanely valuable.