> It contains troll harassment. By not letting a troll know they've been banned, you remove the incentive they might have to create a new account to continue their harassment.

Completely false.

It only adds another step, which is "check account with a private session". I'm sure eventually shadowbanning will also look at what IP address and also lie as well. But right now I don't know any sites that do that.

But shadowbanning is a disgusting practice, and is completely anti-transparency. It can be used to further political agendas (like the article is about). And if an account is spewing troll garbage, just delete, add to a mod log, and close. But very few sites are open like this. (The only site I'm aware of was the old site kuro5hin.org).

edit: And not only shadowbanning, but flags/dead also are abused here on HN. Its all too easy for a legit post with a differing (non-trollish) viewpoint that differs from the status quo, get -1'ed into oblivion, and then summarily flaggedkilled. Again, I've seen this happen when it appeared that there was some sort of concerted campaign to silence certain opinions. Requests to require a comment for flags/-1's, or even a 'who modded this' have gone unanswered.