Maybe YC is just trying to catch elusive human resources in its net and deploy them to projects that have been vetted by its network of advisors and affiliates?

Payments are made in the form of equity or convertible debt - no need for nasty perpetual licenses in the form of royalty payments. If many startup web businesses are not taking in much cash, but are rather meant to be sold on to larger business as interlocking pieces in the advertising money deployment machine, why commit to a stream of cash payments in the future?

No-idea recruiting is a way to shake out people who may be valuable to plug into startups but for some reason are not coming up with the right ideas themselves. Or at least that is my opinion.