What about the comments that are on 1 point and you mean to upvote them but then misclick and they go to zero? At the early stages of discussion that kind of thing can have a huge impact.
My previous comment was downvoted to at least -3 and it rose up again to 1. I think that proves that with enough eyes a good comment will at least get back to 1. Most comments occur on highly trafficked posts, which means most comments should be seen by enough eyes.
Again, in the grand scheme of things one up vote or down vote is relatively unimportant.
it's not about the final score the comment gets, it's about the amount of influence early in the story.
edit: Also, I kicked off the downvoting when you were on 1 point, as an experiment. I wonder if the other 3 people who downvoted to get you to -3 would have done so if I hadn't initially put you at 0. Also, clearly three other people upvoted you. If I hadn't put you at 0 and then 3 others followed my lead, would you now be at +4?
It makes a big difference in the perception of opinion. Simply by initially putting you at 0, I was able to make it seem as though your opinion was worth less than mine. The difference between a +8 comment and a +1 (or -3) comment is much larger than the difference between a +8 and a +4.
You seem to underestimate the value of "emotional state" in a market (or a community). During a recession, comedy and other light entertainment does better because people strongly want to feel better. And people get murdered because they made someone mad. Negative emotional states contribute to the decline of a site -- something pg has repeatedly expressed interest in avoiding. I am not a hacker, so I have no idea what the time investment would be on the back end. But preventing trouble is typically way cheaper (in terms of time and other resources) than cleaning up the mess after the fact.
sorry but I don't measure my hopes for a better HN with PG's needed efforts, but as a simple user that wants things to work well. Also the effort is minimal.
I've probably clicked two or three wrong arrows out of thousands of clicks, which makes it pretty much a non-issue.