Honestly the biggest failing is just SEO spam sites got too good at defeating the algorithm. The amount of bloody listicles or quora nonsense or backlink farming websties that come up in search is crazy.
For most commercial related terms, I suspect if you got rid of all “spanmy” results you would be left with almost nothing. No independent blogger is gonna write about the best credit card with travel points.
This is bullshit the search engines want you to believe. It's trivial to detect sites that "defeat" the algorithm; you simply detect their incentives (ads/affiliate links) instead.
Problem is that no mainstream search engine will do it because they happen to also be in the ad business and wouldn't want to reduce their own revenue stream.
Afaik they did not lost the fight. They stopped trying, because it was good for short term earnings
I feel like google gave up the fight at some point. I think HN had some good articles that indicated that.