While it would be great for founders to get quantitative and qualitative feedback from PG & team, it would be a pretty daunting task for YC partners to give a well thought out answer to the 1000+ groups.
While 1-2 sentence answer from YC could help out your company, it could open up a whole new can of worms that causes some groups to say, "but wait.." or "good idea, we can pivot...".
Their nice rejection letter is probably the best result the non-interviewees can get.
I thought the same thing, except when they are reviewing it they must be taking brief notes like, hey my pet peeve no co-founder, or what ever. All I am saying is if they structured it to say a scale of 1-10 (as in 5 of the reviewer thought you needed a co-founder) or 5 out of 10 think the idea isn't good enough, or 7 of 10 thought the you didn't stand out, etc.
While 1-2 sentence answer from YC could help out your company, it could open up a whole new can of worms that causes some groups to say, "but wait.." or "good idea, we can pivot...".
Their nice rejection letter is probably the best result the non-interviewees can get.