That's fair, since I am not a founder and have no direct personal experience with YC (nor interest in gaining such). My "from what I've seen" is based on reading HN, talking to a friend who was accepted into YC but turned it down, and pg's essays. As such, I will confess that this is a bit of an uninformed cheap shot -- but given the confirmation bias of current and "successful" founders and the political/social pressure on all founders, I'm not sure this viewpoint would be exposed if it existed.
I furthermore admit that my opinion is heavily influenced particularly by that last component; I find pg's seemingly rational exhortations of "how to be successful" to be slanted and self-serving. They are excellent logical argumentative essays that assume a limited definition of success and guide the reader inexorably to the best way to achieve that particular flavor of success while ignoring (and subtly implying the nonexistence of) others. I may be inferring too much about YC's actual behavior from what I glean from those (otherwise excellent) essays.