YC is a for profit entity. Why would they offer a free cup of coffee much less access to the resources and network if they aren't getting anything out of it? I like YC and enjoy HN, but the altruism comes after the profit (as it should).
I just know for many startups like mine $150k is basically worthless. It's not enough to hire and you just stay somewhere cheaper and commute into YC for the program.
As I understood it, the original intent was just to pay living expenses while doing the program and developing a minimum viable product. The intent was that the makers would own the company. It has strayed from that for better or worse.