Exposure != Accumulated comments, especially if you aren't counting distinct authors.
Dig a little deeper, and you'll see that particular submission ("US Supreme Court Upholds Texas Porn ID Law") was visible on the front page for barely five minutes [0] before something abruptly exiled it to to the end of the second page and a slide into obscurity.
In contrast, I randomly picked something from several pages down today that which looks bland with triple-digit comments, and got "A Typology of Candianisms." Turns out that has even more comments (327!) and was visible on the front page for about twenty hours [1].
Quite a difference, isn't it? I'm not against the idea that HN needs to guard its content-mix, but we should not live in denial about it happening.
