I'm not sure why any of this requires third-party cookies or the bloatware that modern websites have become in order to enable this sort of tracking by dozens o

I'm not sure why any of this requires third-party cookies or the bloatware that modern websites have become in order to enable this sort of tracking by dozens of entities. The most healthy and consumer-friendly advertising ecosystems (broadcast/cable TV and podcasts are good examples) are the ones where individual tracking is _not_ possible. As soon as it becomes a pure numbers game tied to individuals, then you get the arms race of fraud and manipulation that has led us to the current terrible state of the web.