Is YC not a marketplace for ideas? Sure, we need to fight for validation of that idea though building them out, getting social proof, floating an MVP... But i

Is YC not a marketplace for ideas? Sure, we need to fight for validation of that idea though building them out, getting social proof, floating an MVP... But in the end - we are vying for our idea to be selected and a stake in that idea purchased through YC investment. Now, PG, can you correct me if I am wrong about hte following. It has been oft repeated that YC is investing in the team -- have you accepted anyone who has come as a single founder and stated "I have no idea what I would make, but here is my CV, history, background -- select me as a YC candidate for backing"? Isn't part of proving out your credentials as a team proving that the team can build upon something, and has an idea to build? Even if that team winds up pivoting off the original? So, maybe it would seem that idea/execution are the yin/yang of success? In as much as potentially team/mentorship is the yin/yang of entrepreneurship?