It's a perk for YC companies. They can post "help wanted" ads on HN. Comments are disabled. Whether that's a good thing or not has been debated ad nauseam, but that's the way it is.
I think it's a good thing to not have comments. They are just focused on hiring. Whether the company is doing great things or evil things - this isn't the time to bash them. It's time for them to hire. If someone wants to write an article blasting them or praising them, they can do that at any time, and post it in Hacker News. But to do it when they are trying to hire - clearly a perk for a YC company. It's just the wrong time.
Interesting. I’ve used HN for a long time but never noticed it before, and was very surprised when I saw it. Almost feels like it should be marked with “promotional”.