I think it’s mostly a result of how easy it is to fire people in much of the US. Is costs many companies (especially big ones) almost nothing to just get rid of a pariah and people know this, so “fire them” has become the easiest way of punishing someone we don’t like. Most people don’t stop to think how much that could ruin someone’s life, so they just go along with the ones who do want to ruin a person’s life.

Also, most fans of "cancel culture" are university students, who don't have an idea what it means to try to pay your mortgage and feed your family. For them it's just a game. A cruel game, but kids often are cruel.