"It clearly says "sponsored content""

Haha no it clearly doesn't. If it was about doing things clearly he would stick to banners and highlighted ads. It doesn't even matter what bias'd SEO guys with twisted morals think, anyway. The majority gets to decide what's right, and obviously the majority thinks it's wrong. Nobody likes to be treated like a fool.

What if when you clicked on a HN story, a third of the time it were an ad? Maybe we could generate false comments to minimize the difference between organic and adverts... Anyway it'd just be content that the webmaster has put there. With a little warning in the footer, to stay morally sound.