Perhaps that could work, although it goes a bit down the road toward heavier and more explicit mechanics, as at Slashdot and Stack Overflow. In another comment somewhere in this thread, pg mentions that he'd like to keep it as simple as possible. Unspoken is the "...but no simpler" part.

It's fun to consider that a dynamic system could provide someone on the back end (or a smart algorithm) with a variable nozzle controlling comment flow.