Originally, Google was very effective at looking at the interconnections of content people had put online and using that to infer which pages were most relevant. SEO tactics immediately started gaming this system to create false signals of relevance, but for many years Google did an impressive job of staying ahead of that game.
I think what finally killed their search quality is the fact that there's no longer a public human-curated network of websites to draw meaning from. Most content on the web is bulk-generated crap, personal blogs and websites are rare, and many passionate hobbyist communities are hidden from crawlers in places like closed Facebook groups.
I think what finally killed their search quality is the fact that there's no longer a public human-curated network of websites to draw meaning from. Most content on the web is bulk-generated crap, personal blogs and websites are rare, and many passionate hobbyist communities are hidden from crawlers in places like closed Facebook groups.