Well yes. They have 2 brilliant guys running an incredibly popular site with a business model of replacing recruiters for their companies, most of which are of interest to an average HN reader.
Let's be conservative and imagine that YC gets them both for a fully loaded total of only half a million per year. (Could be half that, could easily be twice that.) These two run the site and moderate it both. That's already damn impressive. Let's imagine hosting costs YC nothing, somehow. (Apparently it's only run on one machine.)
For the low low price of free you and I are getting a high performance site with astonishingly good moderation and relatively few ads, certainly none that beg for an ad blocker. Of course I expect it to comply with YC's needs but in fact there's an immense amount of criticism of YN and its cohorts.
Now tell me where there's another site with quality this high that's free and keeps its prejudices to a minimum (I say that as a person with politics that probably run afoul of most HN readers).
Even with your tinfoil hat on I'm pretty sure you'll find nothing else remotely close to this good on the web for free.