SocialNetworkingSoftware will fail because real social networks are organized around things. Social networking software is only organized around the abstract idea of the social network.
Doesn't seem entirely plausible, given TribeNet's ability to organize tribes around themes. But may have a point.
The argument in favour of sharp focus seems to miss the possibility of serendipity and the virtue of FractalLoading. And as I argued (somewhere on Tribe), with a general social networking service, you will be connected to different people through different shared interests. On separate themed social networks you'd have fewer connections via these other dimensions.
In a sense, generic social networking software is the negative of the normal, purposful networks we use. It lets us make extra connections around the corners of those networks.
Part of SocialSoftware