Unfortunately I find it's not quite as simple as the first snappy or good idea snowballing into the top comment - I've often noticed a good long chain of replie

Unfortunately I find it's not quite as simple as the first snappy or good idea snowballing into the top comment - I've often noticed a good long chain of replies and discussion get bumped down simply because of the high karma points of the poster of a top level comment. The upside of that is that people with higher karma get their voice heard more easily, which (hopefully) encourages people to slowly build up karma by contributing good links or comments. Yes there's snowballing but also trolls get drowned out quicker.