Here is the problem (and it isn't privacy): A search engine's job is to present you with the best possible results for any given query. A ad is either A) the

Here is the problem (and it isn't privacy): A search engine's job is to present you with the best possible results for any given query. A ad is either A) the best possible result or B) not the best possible result. If the ad is the best possible result, then the search engine must display it anyway in order to fulfill its mission. If it is not the best possible result, the search engine must violate its mission in order to display it. To put it bluntly, advertising is paying to decrease the quality of search results.