I think part of this is the inverse of the base rate fallacy. As people's use of search has gone up, the absolute number of bad experience (many ads, or poor re

I think part of this is the inverse of the base rate fallacy. As people's use of search has gone up, the absolute number of bad experience (many ads, or poor results) has gone up regardless of whether the actual quality had gone up or not. Combine that with the elevated expectation and the confirmation bias, some people's perception of search quality will get worse and the number of people with such opinion will increase.