Google's decline in search quality could be explained a lot of ways. But something that must be a factor is changing from being led by computer scientists to, in 2015, being led by a an MBA from McKinsey. I think MBA dogma is ultimately poisonous to long term quality.

https://arstechnica.com/gadgets/2024/01/google-search-is-losing-the-fight-with-seo-spam-study-says/