Why would banning content farms draw the eye of regulators when the content farms are gaming the search engines? Because search engines fell asleep at the wheel and now content farms are a sizable chunk of the economy? And they can always release some features like curated/customized search to weasel around any regulation dangers. Maybe search engines just don't care about the health of the web.
I don't think OP meant content farms. I think he meant half of the sites that have articles repeatedly appearing on HN. All those smaller and bigger "news" services that write a lot of poor, shallow, lying or just plain wrong, controversial articles. The problem is with incentives - they do it for ad money, not to inform/educate people.