The way it seems to work is that direct replies to highly rated comments need to 'do more work' to stay unfolded (i.e. it needs to gain a higher amount of upvot

The way it seems to work is that direct replies to highly rated comments need to 'do more work' to stay unfolded (i.e. it needs to gain a higher amount of upvotes-per-view). This burden is similarly increased the deeper nested comments get, and possibly the more replies already exist to the parent. It is a deterrence to posting a direct reply to the top comment, since there is a higher chance that the reply gets folded, unless it is high quality. I like this idea that comments have to earn their keep, in a weighted ratio to how visible a space they are trying to claim.