@LukeMorton: That’s a good idea, and in fact I think the best approach is to use a combination of all the involved suggestions in this post and thread.
Hellbanning/slowbanning/errorbanning shouldn’t be tools of first resort – they should be reserved for users who cannot learn to behave better, or who are deliberately trying to be destructive and have no intention of changing their behavior, because public-banning these users just makes them go create new accounts and try again.
Warnings followed by timed suspensions (known to the user) should be the first approach; some users will realize they’ve been misbehaving and improve their behavior. And all such actions taken by moderators should be public, despite the possibility of notoriety; in a democracy, as Jeff puts it, the actions of government need to be public and transparent.
But after the first couple of offenses, or if it’s clear that a user is being intentionally disruptive, moving to hellbanning (maybe not permanently, but for a while) is entirely reasonable.
In fact, it would be interesting to implement a trial system, where when a user is deemed (by mods) to be disruptive, they’re placed on trial, and “jury service” is randomly assigned to users. (Probably you’d try to exclude users who the accused had posted replies to. ;-)) The users individually vote on whether to suspend the user. It could maybe require a unanimous vote, as in a criminal trial, or maybe just a supermajority (two-thirds?). Whether the identities of the jury were known might not have to be public, since they’d be pulled randomly by computer and can issue their verdicts without having to be physically present in the courtroom – instead, the “testimony” would be presented to them on a special page that showed all the accused’ recent posts. There’s all sorts of issues with a trial approach, I’m sure, but the SO sites could be an interesting place for it to be (no pun intended) tried.
A user being able to /ignore other users is something that should always exist. (With an option: Do I see the user’s presence on a thread, but the content of their posts/replies is hidden, or is their presence entirely hidden?) Normally, being ignored by a few people shouldn’t have any effect on whether you end up getting banned, but if you end up getting blocked by a lot of people with high reputation (maybe each user has a “block score” which is the sum of all the reputation of everyone who’s blocked them), then that user should be flagged for the moderators to look into. (Someone who gets blocked occasionally but has been around for a long time might just be crotchety and not harmful, but someone who gets blocked by a huge number of people in a short period would probably indicate malice.)