Yeah, but penalizing people based on metadata or keyword lists is incredibly easy. Compare that to trying to figure out which recipe site is keyword stuffing vs which happens to have a story by someone who really did journey to Tuscany to learn the perfect cacciucco recipe.
Sometimes I've fantasized about Google having human editorial that would evaluate these content farms as they grow and make the nuanced decisions of which to derank. But then, if they really did that, they'd get sued or regulated pretty quickly.
I feel weird arguing for Google's side since I actually do have a lot of criticisms and generally dislike Google search. I just think this content farm issue looks very thorny; humans are built to deceive each other and at some point of sophistication that gets very difficult to control.