This is especially true in the humanities and the social sciences. Where truth is hard to ascertain, and therefore it is easier to substitute political correctness for critical thought.
Note: you can still be an avowed and serious leftist and have my respect if you allow your ideas to be questioned, hold yourself to a standard of proof, and tolerate dissent. What I’m criticizing is the way especially in universities, people jump right to “You’re a Nazi/fascist and the only acceptable response is to shut you down and eject you from the community” if someone doesn’t embrace all the same political dogma as you.
The essay https://www.paulgraham.com/say.html captures the problem perfectly. I think that Paul Graham was completely correct when he said:
"I suspect the biggest source of moral taboos will turn out to be power struggles in which one side only barely has the upper hand. That's where you'll find a group powerful enough to enforce taboos, but weak enough to need them."
Those on the left have been trying to advance their power through creating new taboos that cement their position. But they've misjudged. As a result Trump, by simply speaking to the resulting pain points, has been put on a potential course towards dictator. (Note, he doesn't have to do anything about it - just name the pain.) Will he succeed? Probably not, but he's certainly making a try of it.
Very few on the left are willing to engage in the self-reflection to realize how they have contributed to Trump's rise. It should be obvious - if Trump is an existential threat then you should reach out to people you dislike, who dislike Trump more than you. But no. We've been doubling down on ideological purity. And the horrible result is in the (currently partially demolished) White House.