I know a few people who did very well despite the fact that they were college drop-outs. But what may work for programmers does not work for other people. For starters, writing code is a kind of work in which one's productivity and competence can be easily measured. If you have a lot of projects under your belt, you are essentially demonstrating that you can do stuff, and that is worth more than a diploma itself.

The dangerous thought is assuming that what works for programmers can work for other people. If you want to be a lawyer or a medical doctor, what projects can you have under your belt that demonstrate "can-do"? None?! Promoting the idea that an undergraduate degree is not valuable is an extremely irresponsible thing to do. I know that HN is a hacker community full of can-do over-achievers, but the rest of the world isn't like that... and perhaps it shouldn't be like that.