No, that actually kind of is what you were saying in your previous comment, about what "the forum itself enforces".

You could identify a set of people who are widely respected and listened to, but that's a different thing again from what Lewis is talking about. YC itself is arguably closer, but only tenuously connected in practice to HN social dynamics. I certainly couldn't tell you which members I pay attention to have been through YC (except for the ones who definitely haven't).