Sure. You'd like to think that Americans are decent and civil creatures across the board. The line was crossed by many on the Left, though, when it morphed from practicing and promoting common courtesy to enforcing it, to attacking and punishing those who don't live up to it. And they decided if people didn't live up to it.
That's where it went off the rails. That's where the Left went too far, and still is. And it's also one of the primary factors that Trump tapped into and made him so successful. Now their culture and impulse is to go in EXACTLY the OPPOSITE direction of PC, and they're massively overdoing it. They have no interest in moderation now.
So in that way, the Left played a role in his win. And beyond.