It’s not that hard a problem if you have the resources of a Google.
They just have to do what they’ve always been unwilling to do. Let actual humans help curate it.
It’s obvious when a site is a content farm. It’s obvious when a site has real reviews vs. just pretend reviews and affiliate links. It’s obvious when a site is actual Stack Overflow and when a site is a clone thereof.
The rule should be that only good faith web sites are allowed. Web sites with dark patterns are not allowed. Anyone who is doing any SEO shenanigans gets their entire domain de-indexed permanently. If Google does this, and only this, it will return wonderful useful search results.
I'm kinda looking at it from the other end of the causation: with all their resource, talent, everyone shouting at them on their garbage results to the point specifying individual sites like reddit in the query has become common knowledge...all of this says that changing course is hard.
We might be completely mistaken on the reasons why it's hard, but there's no doubt they can't do it easily.
On human curation, this brings other problems that Google is also very bad at solving. Google would need to manage their moderators at scale. Even Meta couldn't do it in a sustainable way, and Amazon's Mechanical Turk model is also deeply problematic. Amazon itself puts a ton of effort into customer service and yet doesn't keep up with the scams.
Curation and moderation at Google scale is indeed a crazy hard problem.
The rule should be that only good faith web sites are allowed. Web sites with dark patterns are not allowed. Anyone who is doing any SEO shenanigans gets their entire domain de-indexed permanently. If Google does this, and only this, it will return wonderful useful search results.