Would creating a scarcity of number of comments that can be posted a day (say 3 comments a day) make people think twice before commenting and probably reduce DH0 - DH3 type of responses?
Let us assume that X gets n units of utility for every point of karma the community awards.
Let us further assume that the community only awards points of karma for insightful posts/comments. This appears to be a safe assumption.
If X knew that comments/posts were scarce, which under your proposal they would be, then X will attempt to maximize the karma earned from each comment/post by maximizing the insightful nature of each comment/post.
In a way, karma whoring would actually curtail garbage comments/posts, if comments/posts were a scarce resource.
I think you may be overlooking one minor little detail that took me a long time to learn: We have little control of how others will judge our comments.
I have made many comments when I thought, "I nailed it!" and then no one voted or replied at all. Even worse, sometimes downmodded without replies. Other times, I made a smarta$$ remark and it got lots of upvotes. I have a suspicision that the same comment may "perform" very differently depending who else is on-line that day. I finally realized that I should just try to be myself and let the chips fall where they may.
I think the best way to "police" the site is not by limiting anyone, but by prudently using the up and down arrows.