I've also helped many (dozens if not hundreds by now) non-YC startups with their Show HNs, so the truth is actually the opposite of what you say. The goal is to have HN be the most interesting community it can be, because that's how HN serves YC's interests in the long run (https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so...). The global optimization is worth more than the sum of any local ones. We try never to do things that aren't defensible to the community, because the good faith of the community is the only asset HN has. Risking that would be dumb.
You should really supply specific links if you're going to post accusations, so that readers can make up their minds for themselves. Otherwise the community here is going to compare the extremeness of your claims to their lack of any specific information, and discount them.
I've responded in more detail here: https://news.ycombinator.com/item?id=28817827.