Exactly. And in addition, the companies that pay to advertise will pay more when their ads have a better chance of reaching potential customers. This leads to fewer ads needed to generate the same revenue, less wasted ad budget by people who sell the products advertised, and less irrelevant stuff cluttering up your browser window.
And with all that tracking, they also can look if poeple price check items and than rise the price if they come back. Because now they know the customer already decided to buy. Happened with collaborating Flight booking sites.
