I think that posting jobs directly to HN is another perk of being a YC company. As noted in the article, the mods can provide a definitive answer.
For what it is worth:
+ I suspect the value of one good hire for one YC company is potentially orders of magnitude more money to YC than whatever it would charge companies multiplied by all the possible times all the YC companies might pay it.
+ The revenue model of YC does not appear to include charging 'incubation' fees to the companies in its portfolio. To the degree this is true it differentiates YC from many other companies in the business of funding startups in batches and providing early stage support and advice. Again, I suspect this is because YC expects the return value of its investment to correlate with the length of runway a startup has and taking fees shortens the runway.
For what it is worth:
+ I suspect the value of one good hire for one YC company is potentially orders of magnitude more money to YC than whatever it would charge companies multiplied by all the possible times all the YC companies might pay it.
+ The revenue model of YC does not appear to include charging 'incubation' fees to the companies in its portfolio. To the degree this is true it differentiates YC from many other companies in the business of funding startups in batches and providing early stage support and advice. Again, I suspect this is because YC expects the return value of its investment to correlate with the length of runway a startup has and taking fees shortens the runway.
But I am speculating and could be wrong.