Precisely what I was thinking. Rather than assuming the what people have read, simply give less importance to upvotes made to a top comment than to those made to comments below.

I think it would also have to be logarithmic, because being the top comment is MUCH better than being the third comment, while being the 6th comment is only marginally better than being the 8th comment.

Coupled with the stochastic model, it could make it a far more level game.