I've always hated (not really but I've always disliked) people who take pains to be polite in discourse for the same reasons that I dislike people who take pains to frame themselves as victims.

You should get over that (the former). You'll end up hating people simply for not being utterly naive. Getting along with people is necessary if you wish to achieve anything.

Manners are almost always used as a ploy for power.

Yes. It is a kind of power that people are willing to grant you and that, as far as ways to grab power go, has rather good externalities. Start using it.

Manners hinder productive conversation and allow for framing techniques that automatically give certain positions more weight than others.

Both good and bad manners do that. The bad ones make it easier.

I care about downvoting because it reflects widespread ignorance and most people here seem to not recognize the ignorance.

You are wrong. I haven't followed closely enough to know whether the other guy was right but your own behavior in your comments is more than sufficient to get downvoted according to local norms - and you'd be shunned or shamed in most social environments where you tried to pull this crap.