"Maybe a partial explanation is that having a simple shared mental model makes network effects much more powerful. When we think about social software as a user

"Maybe a partial explanation is that having a simple shared mental model makes network effects much more powerful. When we think about social software as a user, we don’t just think about the software, we also think about the network of other users, and it’s important to be confident that we have a shared understanding with those other users. If we’re not confident of that shared understanding, we won’t connect, and the value of the software will diminish." I really agree with this, and I think it's also true from a design perspective. A few of the people who've tried my social microblogging site (mostly people who'd come over from Tumblr, which I find to be pretty anti-social), testing it in isolation without adding any friends, have complained about the lack of control over the design -- you can change the color scheme, but not your style sheet or layout. Meanwhile, users taking advantage of the social features have noted how nice it feels to know that the friends with which you're interacting are all immersed in the same basic interface: through the awareness of shared experience, network effects end up multiplying the value of the design, and the interaction becomes that much more satisfying. So far, I've found it to be well worth the sacrifice in customizability.