I think there's a lot of value to this idea. Think of it as basic network effect/peer pressure/culture thing. Just as you want "more of the right people", you (probably) want to start out on a topic with "more of the interesting/right" comments. That will generally steer the discussion -- as readers adapt to what is being discussed.

This could/should probably be a/b tested (eg: on/off on odd/even numbered submissions or whatnot).