My answer to some common replies:
1) "But the [left/right] is much worse": you're sorta making my point. Even if the other "side" may be worse now, if you're honest with yourself, I'm sure you can see where your partisans have crossed some lines, too. And the whole point of this piece is authoritarianism and fascism grows slowly over time, so "We're slightly further down the fascism hill right now so we're better" isn't a heartening response
2) "This is 'Both sidesism'!!!" First of all, I don't claim there are good people on both sides, I claim there are bad people on both sides. Very bad, sycophantic people who see the worst in others, assume the worst motives, and are willing to stop at nothing, including murder, to achieve their ends. Yes, for many issues there is a "right" and a "wrong" and these could theoretically be discovered through empirical testing and observation. But we're not talking about individual issues here, we're talking about national / political identities and the complex social and tribal bonds that make people even choose "a side" in the first place.
3) "You have to speak out / choose a side, or are you morally complicit in evil" Don't entirely disagree. That said, extremism is polarizing and destructive of rationality and humane discourse, regardless of where it comes from. Just because we are all sort of forced to "pick a side" when the gravitational forces are so strong, that doesn't mean that the side we pick will be right all the time or even a force for moral good, just a temporary stopgap against moral evil. That doesn't mean you don't have a responsibility to identify evil and speak against it when you see it. It's just a lot harder for those people who see much evil amongst two large constituencies that see themselves as wholly Good, than it is for those people who are wholly convinced of their Good and the absolute Evil of the other side.
And although I don't claim to be either rational or in the middle, I do believe I am right about the creeping fascist tendencies present in the polar extremes of American politics -- and there's no better evidence of the truth of my comment that it is being downvoted and commented into oblivion by partisans on both sides :)