Flag it. Flag every submarine ad on Hacker News. It'd be a boon for the site if it treated every positive article from companies with marketing budgets as astroturfing until proven otherwise. Same goes for political articles. And anyone caught at any time trying to game the system. Just blanket deleted for a set period of time. Offend again? Longer time. Third time? You're done. Forever.

The main page would only be cool projects and interesting tech news, instead of flame wars by confused people who think Apple and the rest of FAANG are a football teams. There's literally no downside.