Because it's not just Google. Every web search engine has been getting worse; it's why Google remains "the best" in every head-to-head comparison. The whole web has been getting harder to search.
Then I found Kagi last year who manages to exeed my expectations, proving that my original assumption is correct:
It is still possible to provide good results today, Google just fails at it.
I'm not saying it is easy. But it is possible.
(Extra interesting: Kagi builds on Google and Bing, two engines that drive me crazy, yet Kagi manages to be great!)