Exactly, the user with low-karma is better off posting topics than comments. Comments don't receive nearly as much points as topics do. Even worse, comments require far more thought than blindly submitting links. What is the economic gain the user with low-karma receive from posting comments? Not much.
I know I suggested it, but throttling submission rates based on karma might not be fair to the end users. Once a karma-archy is established, the rich will get richer at the expense of the poor.
Well, I certainly hope that news.yc users are a bit more than Ricardo-programmed economic optimization automata. :)
One solution to older users having a perpetual advantage would be to implement some sort of aging of karma, or at least of the karma value used to determine throttling. Such a thing would actually be a win in terms of SNR--it doesn't really matter how karmic someone was a year ago, if they have only made low-quality posts/comments in the past month, they should be treated (in the submission system) as a low-karma user.
An addendum, stimulated by dinner with dfranke: under certain assumptions about the growth rate of the community, karma ages without any algorithmic intervention: as the community grown, the number of moderators grows, and so the mean and maximum moderation per post increases. As a result, new post are effectively weighted relative to old posts.
The problems, of course, are that there is some fixed point, and also that news.yc may not fit the growth model that makes the above true for a community like Reddit--and that may be a good thing.
Another idea I mentioned elsewhere- if a story gets to the bottom of the new page without any up-marks at all it adversely affects the submitter's karma.
I think this should remain neutral. Ignoring a submissions DOES indicate its worthiness to a point, but sometimes things get missed. Only a true down-mod should degrade the submitter's reputation.
I know I suggested it, but throttling submission rates based on karma might not be fair to the end users. Once a karma-archy is established, the rich will get richer at the expense of the poor.