It may also be (may not, dunno) that a lot of YC applicants are first time entrepreneurs. Many may come from a technical background where they're used to being

It may also be (may not, dunno) that a lot of YC applicants are first time entrepreneurs. Many may come from a technical background where they're used to being the topical expert in most of their meetings with "business types". So, they become business types and suddenly that's no longer the case. So maybe it's not that they've never had constructively critical feedback before, but rather just that they haven't yet had much of it outside their area of expertise?