What would be the point of hiding comments on HN, where the entire point is the comments?

Hence why I enable comments on HN. But most sites are mostly article+comments and in those cases the comments are often pointless.

Is it just using some sort of heuristic to determine the comments? I was thinking that that might have 'rules' for each site individually, which would make no sense for HN (because why bother for a site where the comments are the whole point).