Since I'm the kind of person that likes Stripe's take on email transparency[1], I might just be over-opinionated on the matter when I think that the YC job posts would be better if conversation was able to occur within them.
Some examples:
* Clever - https://news.ycombinator.com/item?id=9082693 - what does code refactoring have to do with that position?
* LivBlends - https://news.ycombinator.com/item?id=9047329 - any YouTube videos of your product in action?
* Mailgun - https://news.ycombinator.com/item?id=7681316 - is there any correlation between the positions and the locations?
Sometimes the conversation is going to be asking for more details. Sometimes making suggestions. Sometimes OT. But I can't think of many situations where inspired conversations would detract from the quality of the posting...
[1] https://stripe.com/blog/email-transparency