Someone can correct me if wrong but I believe tracking can be as simple as monitoring the IP address doing a GET for even a static ad image, which you then save with information such as the referer header to track a person across the internet.
It can. Which is why Brave modifies the referer header, and has integrated support for Private Tabs with Tor (for users who wish to go even deeper into the shadows). Not to mention, by cutting out third-party ads and trackers, you greatly reduce the size of your footprint. The first-party may attempt some degree of tracking, but it would pale in comparison to what presently exists online.
