I was not trolling. My posts were not getting voted down, despite often taking unpopular positions.
I was, however, taking a position that one of the moderators of this site disagreed with, and (without realizing it) wrote a response making an argument in response to a post from one of the Y combinator people.
I was hellbanned for disagreeing with the politburo. It was pure censorship because pg, et. al, cannot tolerate people who disagree with them on a political topic. Ironically, I was taking the pro-startup, pro-capitalist position.
Since people are aware of hellbanning, they should be aware that it is used to silence people for disagreement, not just against trolls.