If you love hackernews why wouldn't you tell anyone about it?
I'll talk about it in person with people I know at work or I'd mention it on my old blog - but I don't want to risk it to the "unwashed masses".
But maybe I'm being too cautious - it is pretty in-depht here. That alone might dissuade most of the shitposters. And the karma-requirements for downvoting seem sufficient.
More people mean a broader dilution of the level of discourse and knowledge, and greater and greater incentives to market / spam / propagandize.
ad free in the sense that there are no obviously in-your-face efforts at graphical marketing; HN is run by a strartup incubator and has a startup focus; flogging your latest release is the raison d'etre of the site.
It’s similar to recommending slate star codex to someone. Unless that person is comfortable with rationally discussing uncomfortable topics, they will think you a nut job who supports everything on the site.