We can't exclude divisive topics altogether—that would not be consistent with the mandate of this site (see https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so... for lots of past explanation about why). So we ask users on all sides of divisive topics to respect the site guidelines, and each other, by posting thoughtfully and not collapsing into flamewar.
Everyone with strong passions feels like the other side is posting inflammatory trash and they themselves are merely providing pushback. This feeling is part of the standard equipment that everyone brings to a flamewar, so you can't let yourself be guided by it.
What you need to do instead (<-- I don't mean "you" personally, I mean all of us) is hold yourself to a higher standard and not break the rules even if other people are breaking them badly. If you make a good faith effort to do that, then you can just about compensate for the default bias of feeling like "the other side started it and did worse" and approximately level the field.