As an Apple investor, I am happy to seem them grow an advertising business. Human attention is the ultimate analog resource. Throughout our lifetime, it will stay in high demand. It cannot be inflated away or commoditized. What I don't get is: How can Apple prevent or even detect that other apps or websites tell Facebook about what you do? If I go to example.com and example.com sends fingerprinting and useage informa…
I don't think they can. As far as I understand what they blocked was the ability of the Facebook app to send Metadata to the website that the user arrived by the action of clicking an ad. They also blocked the website being able to reply to the Facebook app whether the user bought anything. This way users og Facebook ads aren't able to see whether their ads are effective, which lower the value of them.
In principle Facebook and the website could store these events (ad clicking and item buying) on their own servers, and just synchronize once in a while. I don't know if they are working on this or it already exists.
However, Apple could threaten to kick the Facebook app of the platform if it provides this "service" to advertisers.