What's pretty unseemly at this point is how easily large tech organizations can game the HN front page. There are thousands of people affiliated with YC/FAANG reading HN, and they're permitted to vote on submissions in which they have a vested interest.
What makes you think you can walk into a casino and demand that everyone listen to you while you explain how all the games are rigged and everyone is a sucker that is in there?
Or worse jumping up on the roulette table and announcing that changes need to be made so that things are more fair and that the patrons should join you in rising up against such wicked circumstances!
You don't walk into a dealers house and tell everyone they are cutting the product and you shouldn't jump onto a company's web site and proclaim injustice.
Just the fact that this thread has been allowed to exist says something about the tolerance of HN and restraint of it's moderators...
Damnit you sucked me in to being nasty, I'm sorry... I guess it's time to take a break. GN all.
The answer is that YC is extremely aware of how valuable HN is as a source of revenue. It's probably their biggest marketing channel, so it's worth many billions to them. They're not evil or stupid either, which is why dang is the moderator. If YC appointed an evil idiot, HN users would revolt very quickly and HN would become much less valuable.
YC is as tolerant as they are because 1. there's a good person in charge of moderation that leans this way 2. they're smart enough to realize how precarious their position is. It wouldn't take a lot of missteps to create space for an alternative. See: Digg -> reddit.