I think the main reason is that they don't have a good test for who's a bona-fide founder or not: anyone can put up a website or release some iPhone apps and claim they're running a tech startup and are in the process of trying to monetize it. Who's going to read those business plans and filter for the legit ones (and what does legit even mean; estimated likelihood of success?)? Hence the buck-passing to someone else (VCs, angels, or revenue numbers, if you successfully bootstrapped) to make the decision. If your startup's got enough cash or revenues to pay you a salary above some threshhold, you're considered a legit entrepreneur; otherwise, you're merely an "aspiring entrepreneur".