At one time I moderated two large and growing forums - wordpress.org/.com - and there was an ability to shadowban.
You post to a forum, as a mod I see your post and I ban you (for whatever reason) You understandably get angry You make a new account, post again and react angrily to the ban in your post I have no option but to ban you again We end up in a circle This is not good for you or me.
If though I shadowban your anger does not rise, you do not make lots of new accounts and I do not create more work for us both.
For me the key here is that shadowbanning is okay for an established user who one day went off the rails. Let them rant, check their later posts, and remove that shadowban when the calm has returned. But you must check. For new users, just ban, block and use tools to autoblock going forward.
I was a mod on a growing subreddit for almost 10 years. Sometimes a shadow-banned user would post. As a mod we could see the post. We would let the post be published but would also reply along the lines of "You are shadowbanned by the reddit admins. This is how you check [give info] and this is how you appeal [give info]."
Blanket shadowbanning is a bad thing. Such bans must be reviewed.