That's a good point, but I think it would have an unintended negative consequence of punishing late comments, which tend to have low karma but may nonetheless b

That's a good point, but I think it would have an unintended negative consequence of punishing late comments, which tend to have low karma but may nonetheless be worthwhile. It would also punish comments on 'new' threads, which often stagnate with 0 or 1 upvotes.