Personally, I see parallels between the decline of search quality to the fall of Google as a place where every engineer dreamed of working to where they are now.
It’s enshittification. Take something great and squeeze every last penny out of it. It’s everywhere today from Boeing to journalism.
Google used to be ahead of the game against SEO scammers but those dedicated people have left. Ads are the business now.
Also there just aren’t that many quality sites left to index compared to the days before social media doomscrolling became super profitable. All the content is walled up. So naturally search results suffer from that side too.