Earlier quoted context omitted.
Twitter isn't just one thing, it's composed of many communities of various sizes and closeness. Some communities are toxic and enjoy kicking people when they're down, others less so. We tend to recall only the extremes of these big personalities doing bad things. People model behavior every day on Twitter. If people only see or recall others kicking people when they're down, that's what people will expect is the norm…
Twitter isn't just one thing, it's composed of many communities of various sizes and closeness. That's true tautologically in the sense that different people follow different things and interests tend to cluster. But Twitter doesn't have communities that can easily kick people out of their entire group, IE, the only enforcement comes from Twitter's own lax rules. People model behavior every day on Twitter. Sure, on a…
Agree that's a problem, it puts a limit on how close a community can be if it solely relies on Twitter to operate (rather than on their own online or in-person fora). This is one rather legitimate reason for cancelling - its a way for communities to excise members they do not want in the community, using the rules of social engagement available to them on the platform. Cancelled people may still have accounts and be able to interact in other groups of people in the broader twittersphere, but largely become pariahs in the communities they are a part of on twitter. This is why cancelling on twitter is not uniformly a bad thing, it is simply a way for communities to maintain some level of cohesion and shared values within the rules available to them.
As far as trolls, yes that behavior will always exist to some extent online. Mea Culpa is just one way to improve discourse, not a complete solution. The issue in public fora like Twitter is that these types of personalities tend to have outsized impacts on the community, and that's still a problem to solve.