Thanks to Frances Bell for drawing my attention to this article, and to a really useful word. I've been talking about the issues of homophily within social networking sites and practices for some time now, but without having an actual word to describe what it was I was getting at. So cheers Frances!
Homophily in this case was sourced from the article Birds of a Feather: Homophily in Social Networks (2001). McPherson, Smith-Lovin and Cook stitch up the concept in the abstract:
"Similarity breeds connection. This principle—the homophily principle—structures network ties of every type, including marriage, friendship, work, advice, support, information transfer, exchange, comembership, and other types of relationship. The result is that people's personal networks are homogeneous with regard to many sociodemographic, behavioral, and intrapersonal characteristics. Homophily limits people's social worlds in a way that has powerful implications for the information they receive, the attitudes they form, and the interactions they experience. Homophily in race and ethnicity creates the strongest divides in our personal environments, with age, religion, education, occupation, and gender following in roughly that order."
There's no doubting the fact that social networking sites are built around the facilitation of homophily - whether its of general or specific interest (liking 'film' or liking 'Korean cinema', or 'Choi Min-shik', for example) , geographical location, institutional affiliation etc etc. The rise of social search makes this even more explicit. In particular, people search engines which mine social networking sites - (e.g. Explode, Squidwho, Wink, & more each day) - are built around the idea that you can find friends who share your interests across locations, not be bound by your network-flavor affiliation.
The current reality is a bit more hit and miss - blame it on the relatively small volume of white-label social networks, or closed houses, or the lack of tag savvy amongst the general population, but it's going to be easier for a while to find someone with very broad interests (for some reason, sex springs to mind as a popularly listed one), rather than your specific long-tail requirements for some time to come.
The question I was asking is what we miss by reinforcing homophily as the prime directive online. To give a pretty flip example, I don't have a huge amount of friends over at last.fm, but I certainly don't want to make friends with anyone who listens to exactly the same music as I do. What would be the point? I want friends who listen to things I've never heard of, and am unlikely to stumble over by myself. I like to listen to new stuff, even if I only very very rarely fall in love with something.