You know, you make an interesting point. I think you're referring to the same thing that the author is referring to.
On the left side of the political spectrum, It's not a single phenomena though, I think you can break it down into two camps on the left:
1. older-school globalist liberals. Probably older, supported the Clintons, ect. These people seem to have traditionally looked down on the right as backward, uneducated "basket of deplorables" or whatever. Plays into the ivory tower liberal stereotype.
2. New-school farther left. Probably younger, fans of AOC et al. They'd also be likely to look down their noses, but in more of a moral superiority perspective.
I think the condescension of #1 goes back decades and has already borne its fruit in (at least to a degree) the political situation we find ourselves in today. I worry that group # 2 hasn't learned those lessons and is proving that they'll just repeat the same mistakes. Unless they self-destruct arguing about Israel, which totally mystifies me.
That said... so much of what comes out of the right is complete and utter bullshit. From the massive propaganda machine that is fox, to infowars, to tiny hyper-racist subreddits — there's a lot of noise to separate from the signal that might be a valid, reasonable conservative argument.
With that in mind, sometimes I wonder if we don't need a bit more contempt.
Maybe if the type of outright hate speech the mainstream right seems to support was not acceptable, that would open the floor for some actual conversation.
To summarize: I wish that democrats and the left weren't been so quick to dismiss legitimate concerns from everyone outside of NYC and SF (hyperbolic, I know). But it's right wing (and especially religiously-motivated) politics that have completely skewered our politics and media.
Saying "fuck that and fuck you" to anyone who supports that system is a reasonable reaction, in my opinion.
But where does that leave us? I don't know.