Well, I guess it could end up creating a culture of differentiated commenting, but at Reddit/Twitter scale I’d be a bit skeptical.
One other worry is that those commentees who are willing to spend significant time moderating the comments they receive may not be exactly those who care about quality. To be honest, I wouldn’t want having to moderate the replies I get on HN. :)
Selecting, from critical comments, only the easiest to dunk on would seem to be likely, and is a tactic suggested by the site name (after all, it's a well-known technique used in screening callers to radio shows...)
Good point. I’d also expect speculation or accusation of suppressing certain replies to become a topic of discussion. Factions will accumulate in separate subthreads where they mutually approve their respective positions, creating mini filter bubbles.
One other worry is that those commentees who are willing to spend significant time moderating the comments they receive may not be exactly those who care about quality. To be honest, I wouldn’t want having to moderate the replies I get on HN. :)