Google has stopped all of the things that allowed it to become the industry leader.That magic started dwindling about 6 years ago when they eliminated Boolean operators. Now, quotation marks don't even work reliably. People had a hard time using it and couldn't get it to return the results they wanted it to. It seems that a large number of people aren't capable of expressing their thoughts in a way that is structured or precise enough to formulate a proper query. So, in order to help them get the results they wanted, rather than the results most closely matching what they typed in, Google changed how it interprets a query.
Now, it guesses what the lowest common denominator probably meant when they typed that into the search box. If you've seen the inane things that some people type into the Google search box and how unclear related it is to what they actually wanted, you know what I'm talking about. Many people do not seem to be capable of understanding the underlying logic. They include words that aren't really what they want. When they don't get enough results, they make their query even more specific. When the results are only partially related, they make their query more general.
I suspect that these kinds of people are also the most likely to click on the ads, not even understanding that there is a difference between the real results and the advertising. Even if they weren't more likely to click on the ads, they make up a substantial portion of Google Search users, so Google adapted to them.