They are not a good way to stop spammers, the bot can easily make a comment and check if its there when it is not logged in. But it is a good way to annoy HN users when they get banned.
I agree. I liken it to "security through obscurity". I imagine it would be quite upsetting to be posting as a reasonable community member, and suddenly discover through some external means that my account had been silently black-holed, without being notified that my behavior was violating some of the community norms before-hand.
But perhaps such measures are needed to defend against the non-bot trolls and other belligerent individuals, and only implemented after numerous attempts at corrective feedback have failed.
"only implemented after numerous attempts at corrective feedback have failed."
That's not how it works. You say something that offends some random moderator, and he/she can trivially silent-ban you. No comment under your comment saying you will be banned etc.
But perhaps such measures are needed to defend against the non-bot trolls and other belligerent individuals, and only implemented after numerous attempts at corrective feedback have failed.