No doubt it has been misused at some point or another, but shadow banning in the context of online communities is generally a last-resort defense against the very worst and most prolific trolls. Not someone who accidentally breaks forum etiquette one time.
A person who is shadow banned generally continues their antisocial behavior in the face of multiple warnings and reprimands. I don't see it as cruel. I see it as defending the community against those who get pleasure out of trying to wreck it. It's effective because the bannee is generally too dim to realize what has happened to them until they get bored and go away.
In regular communities, maybe, but that kind of abuse is rampant on platforms : I was shadowbanned on Reddit as a new user, and still regularly get shadowbanned in YouTube comments (seemingly if I dare to post more than one comment, or if I dare to add a link, including a timelink to the very video!)
A person who is shadow banned generally continues their antisocial behavior in the face of multiple warnings and reprimands. I don't see it as cruel. I see it as defending the community against those who get pleasure out of trying to wreck it. It's effective because the bannee is generally too dim to realize what has happened to them until they get bored and go away.