It isn't so much that 'google doesn't know how to filter them out' but there's nothing left after having filtered them out.

Nobody is producing real content that isn't behind a paywall.

There's nothing to find.

There is real content being drowned out by autogenerated SEO crap. I tried looking for rice cookers which didn't have non stick coatings, they do exist and some blog posts which talk about them but the top results are all stores which have just a generic category for rice cooker but generate 200 duplicate pages with the title changed to exactly match whatever your search term is. So it says "Ceramic rice cooker" but shows their generic listing of PTFE rice cookers.

Google search is constantly improving but the SEO spammers are improving faster.

I know this isn't true because I've used google for nearly two decades with good results. That information hasn't evaporated, it's just buried.

Fair. The fact that Google exists + the fact that Google serves a huge amount of traffic + the fact that Google is unable / unwilling to filter out content farms = incentive to content farm.

If there were no Google though, we'd likely have the same thing.

So I guess the only reality that avoids incentivizing them is one where (1) there is a massive traffic generator & (2) that massive traffic generator severely disincentizes content farms.