I think part of the problem is an upvoted reply post doesn't filter to the top of the page, it's tied to the rank of its parent. A +10 reply post, replying to a -3 top-level post, will be seen by no one, despite being highly valued by the 10 people who did see it. A -5 reply post to a +6 top-level post will still be in reasonable scrolling range.
Top-level posts have a major visibility advantage over reply posts, and thus have a karma advantage.
I wonder if weighting a top-level post's score by the score of its children would help alleviate this. On one hand, there could be more rewards for trolling, since a troll that attracts popular refutations will be visible. On the other hand, a civil post that is both upvoted itself, and invites interesting upvoted discussion, will outrank the troll post.
Maybe we should negatively weight "awarded karma" by the height a comment is on the page.
A 100 point comment that is two or three screens down and buried in a nest of mediocre comments is almost certainly better than a 100 point top level comment at the top of a discussion. The later is a much more difficult and impressive feat.
Comments would have the same point values, but the value that is added to the user's karma score would be weighted. Getting lots of points would still make you feel good about your comment, but it would neutralize more ...strategic karma farming.
Few people will agree with me and they're never going to implement it, but I think comments shouldn't carry karma. It just encourages too much pettiness.
Top-level posts have a major visibility advantage over reply posts, and thus have a karma advantage.
I wonder if weighting a top-level post's score by the score of its children would help alleviate this. On one hand, there could be more rewards for trolling, since a troll that attracts popular refutations will be visible. On the other hand, a civil post that is both upvoted itself, and invites interesting upvoted discussion, will outrank the troll post.