The community is very important. But there's something to be said for the ability to filter properly - there was a blog post on HN recently discussing how aggregate sites end up with the lowest common denominator. What ends up on the first page is only a small % of the submissions that are actually interesting. I probably miss half of the stories that I would like just because they fall off before I even see them.
The question is, how do you figure out what's interesting to who? Joel is attempting to answer this for himself. A site that could answer it for everyone while still somehow maintaining social bonds would do very well I think.