Another reason I think the valley works so well is the audience its news outlets have. If you have a great product but can't get news coverage on it, its going to be hard to get growth without a large marketing budget. However, if you're friends with a friend of a Techcrunch write, its much easier to get covered and start to get a core group of users who love your product - and are tech savvy enough to understand that features that don't exist yet will be coming, and they should be patient.

If you try to bootstrap a startup without using SV's media outlets (as would be the case for people who don't have connections to these folks), you're going to have a much harder time.