First and foremost, I think this just fundamentally wouldn’t work out because it requires enough people being on a given thread at the same time, which would be on the rare side for most threads, then on top of that they also need to be in a position to talk freely, ie - Not on the toilet, not in their open floorplan cube at work. The two place most commenting happens.
More subjectively, IMO, the times this would work out and be civil and a good conversation, would be far outweighed by the ones where it went south.