There's several hundred Y Combinator companies, but I don't think I've seen a commensurate number of posts to HN. You'd know if it was open slather on Y Combinator companies posting self-promotion material to HN because this post would not be at the top, it would be some launch page for a company ending in 'ly'.

I typically only notice YC companies mentioned here when it is a Techcrunch (or similar) article about them.

It's as if a community of programmers and engineers can't understand the various weights a ranking algorithm can take into account outside of plain "2 > 1".

Stunning.