Ask HN: Why does HN not allow comments under Hiring posts?

The quality of comments isn't high enough. You can see it in the monthly who-is-hiring thread when you paginate to the last page. It's a mix of people asking about the job (one can contact the company directly), asking about previous encounters ("I sent you my CV two months ago!") or complaining ("why is this on HN at all?").

The real reason might be that Hackernews is a YCombinator project, all job ads on the frontpage are reserved for YCombinator startups, and they don't want to attract negative comments. I don't know, I don't want to speculate too much.

These are ads, many platforms forbid comments on ads. The typical off-topic comments we get on the monthly who's hiring post is probably what they are trying to avoid.