Some dotcoms could have succeeded if computing and bandwidth was 10x cheaper. Others could have succeeded if the Internet had 10x more users. That's why some successful Web 2.0 startups are very similar to failed Web 1.0 startups. Starting a company five years too early could be considered a form of business stupidity. Of course, free shipping for pet food is still a bad idea.
The "10x more users" thing sounds suspiciously like social network sites, but the expert opinions I've heard on those have suggested that the failure wasn't a lack of traction but bad policy.
And that's before the complete lack of monetization, a business model that didn't seem to really take off until Google figured out how to do it well.
