Well, most comments on the net are utter shite. I don't blame them. Hacker News is different, but you don't have to go further than arstechnica to see the start of rapidly declining comment quality. A mainstream publication like NYT? Hats of to them if they manage an open discussion that's not just trolling, hatred, keyboard warriors and bigotry. I'll believe it when I see it. Just read the comments to The Economist. You'd think such an archetypically highbrow publication would have highbrow comments. You'd be wrong. Only niche websites have good comments.
I guess some spamfilter-like technology could be applied to filter out bad ones, though. Wikipedia also has an engine to filter out bad edits. Should have lots in common.
I find it interesting to compare "second tier" 4chan boards like /g/ (technology) to the discussion boards of other websites (like arstechnica). Typically, a place like /g/ compares very well, if not better.
Sites like to blame things like the "Greater Internet Fuckwad Theory", but I think most of the blame lays on the site for having poor moderation.
4chan's moderation is mostly just filtering for child porn. /g/ being good is because it's a niche place. Proper moderation costs proper money, and proper moderation doesn't scale. Moderation can't be the solution.
But crowd-sourced moderation like reddit/HN scales really well: Let the users do the hard work of flagging/voting and a small community of moderators to do orientation-related work.
Outside of /b/ (and one or two 'containment' boards), they do a pretty decent job of modding out hate-speech. Throughout, even on /b/, they keep shitposting (posts intended to do nothing but lower the signal/noise ratio, pushing active discussions towards expiration) way down. I would argue down below the levels seen even on default subreddits. Reddit has a serious shitposting problem.
I guess some spamfilter-like technology could be applied to filter out bad ones, though. Wikipedia also has an engine to filter out bad edits. Should have lots in common.