I very much understand and appreciate the frustration. I think you should cut your fellow members a bit of slack. There are assumptions in your comment here that may not be entirely accurate or at least aren't representing the whole picture. I'm going to attempt to provide alternative perspectives here: I'm not claiming they're correct, but are an attempt to broaden what other's may be perceiving. That doesn't mean their perceptions are correct or even fair.
> "automatic downvoting"
Let's set aside the idea that they're automatic for a moment. Unless your mind reading skills are better than mine, it's hard to know the intent from a downvote alone. You can't even know who did it, other than it's not the person you responded to.
> "of non-controversial, easily-proven statements"
Even these may not be constructive to the conversation. They may be tangential, irrelevant, or intentionally misleading. Members may downvote for any of these reasons.
> "comments with highly subjective and inflammatory takes get upvoted show the worst this community has to offer."
Yeah, highly charged comments can get upvoted: emotions are a powerful thing, and there's a lot of evidence (is it even controversial at this point?) that emotions fire before rational thought. And there's increasing evidence that our rationality actual does more to rationalize our emotions than work as some sort of logic engine. People have to work against this, and that, indeed, is effort. Frustrating? Incredibly so. Human? Very.
That's not to say we shouldn't work against this, at least some of the time. Internet fora make this all the more difficult because we're engaging with such limited bandwidth. We don't get to hear tone, or see facial expressions. We only have this limited text stream, and so we're likely bringing a lot more of ourselves to fill in the gaps than we often realize.
There's a lot of charged language in your comment here. That's just an observation, not a judgement. How should I respond to that? Should I attempt to put it to the side and respond in a way I think is most effective? Or should I write you off as some hot head that can't control their commenting, going against site guidelines by complaining about voting? Or just silently downvote you for doing so? I often get the impression that that's how some members perceive others as behaving. I don't think that's a useful starting point from which to improve HN, so it's one I consciously choose not to take.
> "a small number of users"
I think it's a combination of a small number of users and the fact that each of us—just because we're human—can sometimes slip. What we can do the rest of the time is not let the slip-ups of others make us respond in kind. It takes more than one person to spread the flames.
Help make HN the place you want it to be. Submit good articles. Write good comments. Upvote good articles and comments. Downvote and flag those you don't think are appropriate for HN. It sounds like you follow HN, so you know how threads on contentious articles go. Do what you can to make it better. (And make a conscious effort to not make it worse.) That includes commenting within the guidelines, such as not commenting on downvotes or mentioning you're flagging articles or complaining that a submission is inappropriate for HN. If you really think there's abuse going on, do contact the mods via the contact link in the footer: they want members to bring things like that to their attention so they can address it.
Honestly, there's really little else you can do, but I think it's enough. Which is why I'm taking the time for this comment. Anyway, best wishes.