The ad industry has proven very good at finding new ways to track people, defeating each new approach to block tracking. They've proven similarly good at learning to infer things they haven't actually been directly told, which is very helpful for getting around regulatory barriers.
In practice, not everyone keeps up on their patches, meaning they tend to be vulnerable to known tracking methods. Total ad blocking prevalence is not as high as one might guess: https://digiday.com/media/ad-blocking-charts/
Additionally, neither Apple nor Google is incentivized to make it easy to block ads on their devices. The only people I know who have done so are ones who have gone to non-trivial lengths to accomplish this.
In practice, not everyone keeps up on their patches, meaning they tend to be vulnerable to known tracking methods. Total ad blocking prevalence is not as high as one might guess: https://digiday.com/media/ad-blocking-charts/
Additionally, neither Apple nor Google is incentivized to make it easy to block ads on their devices. The only people I know who have done so are ones who have gone to non-trivial lengths to accomplish this.
Sadly, I think you may be excessively optimistic.