Earlier quoted context omitted.
It is funny, because I agree with your statement. But I never thought of Reddit as made for discussion. Maybe I miss out, but I always have a terrible time following the comments on Reddit (granted I don't even try on Digg and comparing Reddit to HN might be apples to oranges). The comments are usually confusing and non-beneficial to me.
I get great mileage out of this "hide replies to comments" bookmarklet - it allows me to quickly read the best-rated comments that reply directly to the article. If a comment is thought-provoking I'll click through to see what discussion it's spawned. http://gist.github.com/582630
i recommend sorting comments by "best", and then just cranking up your minimum score rating in your preferences so that comments under, say, 10 will not get shown.