The ability to post job ads directly to the front page of HN is a YC perk, as is the right to do it without allowing comments on the ads.
For a long time the policy has been that only YC cos can post to /jobs, but once a month we have whoishiring threads which are open to everyone. It doesn't seem an unreasonable balance to me, given that YC funds HN and asks (almost) nothing else of it [1]. I also like that it's completely clear and up front. But I'm interested in opposing views, if you'd like to share them.
[1] Re that "almost": the other YC-specific privilege on HN is that founders' names show up in orange. (PG did that years ago when there were beginning to be too many YC founders for them all to know each other.) Unless I'm forgetting something, that's literally everything.
Edit: several years later, in 2017, we added Launch HN posts (https://news.ycombinator.com/launches). Those get placed on the front page like job ads do at first, but after that they are subject to upvotes and open to comments.
Also, regarding no commenting on job ads, I think this is better for HN. Otherwise, the attention of HN is thrown into threads that are promotional spots.
I think another benefit of HN is that YC keeps its name relevant to a great many potential entrepreneurs.