Noah Smith makes a good point in this article that ‘cancel culture’ has always existed, we just called it ‘social ostracism’. The difference is the technology we interact with, and the intended and unintended audiences with which we communicate.
First let’s think about distribution. In the olden days, you could “read the room” and decide whether you were going to get a sympathetic ear before you said something. You knew who you were hanging out with — your relatives, or your coworkers, or your buddies, or your neighbors, or your cell of the Communist Party, etc. On the internet, that’s much less true. On Twitter, anyone can see what you write and retweet it or screenshot it to millions of strangers all over the globe. In a Facebook group, you probably don’t know exactly what kind of others are in the group unless it’s really small. If you put something up on a website, anyone can read it. Etc.
The internet also makes it much less hard to maintain private spaces because text can be screenshotted and distributed widely. In the old days, if you said something that would be cancel-worthy outside the group of people you were talking to, it was impossible for someone to verifiably transmit that information outside the group — they could snitch on you, but it would be hearsay and you could deny it. But when you write something down, the text of what you wrote can be screenshotted and distributed widely to people that you didn’t expect to be watching you.
Now, this broad distribution has a number of effects. It makes it a lot harder to get together with your buddies in private and say racist or sexist stuff, because now one of them can betray you with a screenshot. Lots of people are probably pleased with that outcome.
But it also means that everyone who talks on the internet must always worry about their words being shown to someone who’s going to interpret it in an uncharitable way.
Thus, the internet changes Cancel Culture by massively increasing the number of people who can target you for ostracism. It’s a bit like living in a gossipy small town where you don’t know any of your neighbors — you don’t know who’s going to read what you write, so you don’t know how people are going to take what you say.