You're right. A lot of articles are paywalled, extermely padded advertising vehicles which people come to the comments to avoid. The audience might be reacting accordingly.
The better and more readable articles linked on HN could demonstrate this phenomena, if the audience shows better comments underneath them. I haven't looked for the correlation before.
The interesting articles which I find in the RSS feed but not on the frontpage nor elsewhere on HN are neither paywalled nor padded with advertisments; either they got lost in the flood of irrelevant articles or did not receive points for other reasons; the one point I can award does little to change that.
The better and more readable articles linked on HN could demonstrate this phenomena, if the audience shows better comments underneath them. I haven't looked for the correlation before.