The problem here is that someone who consistently provides high-quality (or at least frequently-upvoted) comments / submissions will likely have less of a contribution than someone with significantly lower karma. For instance: you would have (slightly) more influence than someone with 3000 karma and an average of 5.
Then this will reduce the amount of impact they have on the community as a whole. They will be doing us a favor by starting out ruining their karma.
Also, to state the obvious, every member here was a new member at one time and I'm not ready to say that is "typical" behavior. It's just very memorable behavior.
The whole reason why I submitted this was because PG said it wasn't the comments that cause issues but that bad comments were getting upvoted too much.