Do they, necessarily? I've suggested that it is understandable but evidently imperfect—the evidence being the consequence that good non-incumbent content is often unseen. In fact, Slashdot's entire moderation approach reinforces that consequence.
I'm not saying Slashdot should abandon its approach, I'm not even saying that it doesn't work somewhat well. But it has a cost and that cost is much higher for a large community with a large volume of user-generated content. And I think that is worth discussing.
I'm trying to provide some insight into the rough edges of Slashdot's management of user-generated content. If you aren't interested in discussing those rough edges (and so far you have not done so at all), I'm not sure what you are trying to do. Game the incumbent advantage by getting your comment close to another one with a higher mod score? Doesn't that just underscore the problem?