to HnNoPassMailer: (can't reply directly)
Moderators (or perhaps some automated system) seem to be quite trigger-happy on the hellbannings. That is the kind of ban where you disappear for everybody else (unless they got `showdead` enabled), but the person themselves has no idea what's going on, or why.
I even saw a guy here get hellbanned for a rather tasteless joke. It certainly deserved all the downvotes it must have gotten and was sufficiently inappropriate to at least warrant a warning, suspension or perhaps even an actual ban. But hellbanning is completely counterproductive in these situations. The guy just continued posting for weeks, completely oblivious to the fact that nobody was replying to him, or upvoting him! Let alone that he had any idea he did something wrong. (IMO a warning would have sufficed on first offence since the rest of his comments were constructive enough, he was no troll)
This is a very good essay on the pros, cons and uses of hellbans (and other sneaky+unusual sanctions such as slowbans and errorbans): http://www.codinghorror.com/blog/2011/06/suspension-ban-or-h...
In summary: hellbans are only useful against repeatedly banned disruptive trolls that won't listen to reason and will just proxy back in with a new account after you IP-ban them because it delays them and they may get bored give up and go away. A temporary hellban is the most useless thing ever, it just wastes people's time and if they are bad enough they deserved that, you probably didn't want to let them back in later. A hellban can be mildly effective to spammers but not much since they expect or detect it sooner.
Personally I've found the slowban to be most effective against the most stubborn and disruptive return trolls (and only those). There's even science to point out that pageload delays directly reduce participation, which is exactly what you want. But the forum I admin attracts those types by its very nature, while in the 1.5yr I've been on HN, I actually haven't seen any of such trolls. The up/downvote system works too well for that (to the point that it sometimes tips the balance the other way into circlejerk territory, but that's another discussion).
This IMO not-always-correct-or-effective moderating is why I have `show dead` turned on, and sometimes when I'm paranoid, check from a different IP if my comments are still visible :-)