It's all about clear standards and strong moderation. I visit another forum that has a great community. No karma, no voting, just those two things. I've also run a large community in the past that I believe was successful for those reasons.
The moderation is strong but not heavy-handed. The clear standards allow commenters to understand why they get downvoted or flagged which is nice. I have seen nitpicky over-active moderators on a different forum site effectively wipe out community engagement over the course of a year and it wasn't fun.
I'd probably just abolish downvoting entirely: rely entirely on upvoting. There's already a bias towards upvoting in the system due to the min cap but not the max cap.
You make it sound like voting-as-disagreement is rare but in my experience it's by far the most common way downvotes are used. I have showdead switched on and I keep toying with the idea of finding an extension to un-grey comments, because over and over I find comments in grey that are well written, erudite and merely express an opinion that goes against the current startup-culture HN zeitgeist. They aren't actually bad comments though.
So why not just let good comments rise to the top.
Perhaps you are right. I have experienced downvotes primarily in semi politicized discussions like automation, economics blockchain, diversity discussions. Most technical posts seems fairly balanced.
Perhaps yeah abolish downvote and only have flag for admins and people with high karma is a good idea.
That seems like a decent idea but a bit tedious for the voter. I also like the Stack Overflow model where each downvote costs 1 of your own karma points.
