How could a startup take that sort of chance on someone, though? Hiring and firing is the most important job you have as you scale beyond a small team. A big mistake at this early stage could sink a startup, while getting it right could be the key to explosive success. Without a portfolio, you're guessing.
Also, someone who excels in the corporate world, where there are a dozen people working on the website, a dozen people working on any given project, and a couple of managers to make sure it all blends seamlessly, may not do so well in an environment where they are expected to create and deploy without guidance or oversight.
I completely agree that startup should minimize chance on hiring wrong people (that is reason I'm arguing that pay in startup must be market rate (no 20% less as many startup try) - otherwise your are gambling with the most important asset you have).
Yes, without a portfolio, you're guessing, but the problem with requiring candidate to have portfolio is that you will narrow the search to consulting/freelancer group which might not be the best pool of candidates.
Also many intelligent people which had startups or consulting end up working for corporations (Comcast, Apple, Oracle, etc.) because... because they are very very good and corporation pay with gold to get these kind of guys.
Also, someone who excels in the corporate world, where there are a dozen people working on the website, a dozen people working on any given project, and a couple of managers to make sure it all blends seamlessly, may not do so well in an environment where they are expected to create and deploy without guidance or oversight.