PG has said in the past that there is a flamewar detector, and that it suppresses discussions. In the past, this has been triggered on certain Microsoft related articles, which has caused several people to claim that there is some sort of ring of HN users who strategically flag articles about Microsoft off the page (and depending on who you ask, they also vote up Google articles). Ironically, it seems that at least some of the people making these claims were sock-puppeting themselves.
PG's comment explaining it: https://news.ycombinator.com/item?id=6596311
In fact this article does consider the flamewar detector. How accurate it is in it's claims, I do not know.