If YC chooses to invest in an applicant, it probably offers great advice to the start-up. If it chooses not to, would you consider that rejection candid advice that the start-up is wrong?

There's an adjective for that kind of thinking, which I won't use because in context of hn it would be downvote suicide.

And yes, I know you're THE pg, but other investors, like Fred Wilson, John Doerr or Marc Andreessen are also THE investors.

The argument that I would find more persuasive would be that YC can help because it's willing to take more risks on "out there" ideas due to dramatically lower investment in any one startup and higher number of startups it funds.

Ebay for Spaces is a very clever shorthand, but it seems just abstract enough to question without a concrete instance. Now, of course, it is one of those brilliant with hindsight instances that seem easy but require immense dedication.