I have been reading HN for years, and I disagree with the premise that there is a "downward slide". For people like me, it might be helpful to provide some sort of evidence to support your claim.
The solution you are proposing also would silence users accounts permanently without any chance for redemption, those users would become disaffected and resentful, and with the trivial nature of account creation here, might cause new problems.
HN is a community, and I think a system that promotes corrective behavior (like the current one) works best when it exerts negative social pressure for "bad" posts and helps new users integrate themselves into the community.
If you've ever seen the movie "Hackers", the character "Joey" is a total noob, and the other characters are constantly giving him negative feedback when he does something stupid, eventually he learns a few things and becomes more useful.
The solution you are proposing also would silence users accounts permanently without any chance for redemption, those users would become disaffected and resentful, and with the trivial nature of account creation here, might cause new problems.
HN is a community, and I think a system that promotes corrective behavior (like the current one) works best when it exerts negative social pressure for "bad" posts and helps new users integrate themselves into the community.
If you've ever seen the movie "Hackers", the character "Joey" is a total noob, and the other characters are constantly giving him negative feedback when he does something stupid, eventually he learns a few things and becomes more useful.