Google built things that circumvent it.

I love how commercials "follow you around". If I search for diamond rings in a browser on one computer, they suddenly materialize everywhere.

I tried it with Duck-Duck-go, searching for something I nearly never search for, something such that the ads follow you around. I just searched in DDG, but did not go to the end website. I then resumed non-DDG browsing, and those came up as ads. I don't know if they are looking at image caches, or loading javascript libraries.

They have a way around it already, and it runs.