I think millennial cancel culture falls under the "fear of rapid change" heading.
Before the Internet went big and mainstream we were in an era I've heard termed managerial democracy. Big media was able to largely regulate the Overton window. Social activists were able, by getting into big media via the path of the universities, to push things like racism and homophobia out of the Overton window and keep them out. This largely worked, creating the illusion (and I now firmly believe it was an illusion) that these things were dying or dead. I remember growing up in the 90s and thinking racism was something maybe a few old geezers in the South believed. "Sure grandpa, the South will rise again, now lets get you your meds."
Personally I see this as well-intentioned, but that's because I think racism is a low form of primate tribalism.
Then the net came along and made it so any yahoo with a few bucks could post. Couple that with algorithms that tend to elevate controversial (thus engaging) content, and racism and all the other banished isms vaulted back onto the stage. They were never dead IMHO, just out of polite discourse. I didn't realize that growing up but I sure see it now.
Lefty cancel culture was an attempt to repeat the purge of those things from big media with the Internet and it didn't work and couldn't work. I did and still do sympathize but I think it's pissing into a hurricane.
Of course there's plenty of right wing cancel culture too that we're seeing now. That's a different beast. Cancel culture historically is a creature of the right. The left form is probably a brief historical aberration brought about by the conditions I outlined above. I'm hearing lefties admit defeat on this right now, and some question whether it was a good idea to try.
Racism won't be dead until people actually change their hearts and minds. Controlling the discourse just means you don't hear about it.