Four relevant bullet points from the Hacker News Guidelines:

* When disagreeing, please reply to the argument instead of calling names.

* Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.

* Please don't post shallow dismissals

* Please don't post insinuations about astroturfing, shilling, brigading, foreign agents, and the like. It degrades discussion and is usually mistaken.

And yet not once does it mention "don't start commenting on divisive topics"