My intuition is that Cancel Culture operates a lot like the Drug War. The vast majority of non-PC speech and illicit drug use skirts by the Eye of Sauron without getting caught. But every now and then some poor bastard has his life ruined because he's in the wrong place at the wrong time.

Saying that Cancel Culture doesn't do harm because people aren't afraid to wear a MAGA hat, is like saying the Drug War doesn't do harm because people aren't afraid to drop acid. Regardless of what percentage of people are caught, it's unjust to destroy someone's life because they put the wrong substance in their body or the wrong idea in their mind.