They did not screw the real user, they just made them invisible. Eventually, when their posts did not get the replies they were looking for, they might just give up and go away -- this was the intent of the system.
I've noticed dozens of hellbanned users still posting on HN, and it was never the right treatment except for one of them (the losethos guy).
But even for them it's a rarely (and specifically) used tool in a large suite of techniques: they give public timeouts and probations, bannings just cost another $10 to reactivate your account, permabannings mean you have to pay $10 for a new independent one. Hellbannings are for situations where the annoyance of the user's reaction far outweighs any interest from the community — the kind of crazy users who despite being uninvested in the community, will sue you over it and retain Orly Taitz.