At the time of the criticisms, Google argued that the technology is useless, as advertisers are not required to obey the user's tracking preferences and it remains unclear as to what constitutes tracking (as opposed to storing statistical data or user preferences).
Moreover, Pól Mac and Douglas J. (2016) in their study "Don'T Let Google Know I'M Lonely", presented strong evidence that the two giant techs have very high accuracy while providing results based on user's sensitive entries.