That is the usual argument, but I don't see how it stands up to scrutiny.
Either there are alternative ways to track a user of an Apple device without IDFA or there are not. If there are, then it is reasonable to assume that unethical advertisers will return to using them if their access to IDFA is gated.
So, whether or not IDFA exists, the only robust way to protect users is to block apps from having access to anything about the host device that implicitly provides a unique method of identifying the user.
This is what other platforms have been trying to achieve. For example, in the web browser ecosystem, software has been restricting programmatic access to features that can be used for fingerprinting or deliberately reducing the level of detail exposed by some APIs.
With control of the entire ecosystem, why is Apple not better placed to adopt this strategy than anyone else, and whether or not Apple is technically capable of achieving the perfect result, how does introducing IDFA make any difference?
It does seem like when IDFA goes, apps will be struggling for identifers, at least on iOS. I've seen a few articles suggesting they will be back to trying to fingerprint devices (in manners that break the App Store terms of service).
I agree entirely - it seems that the solution going forwards is to prevent any access to any kind of persistent identifier that is part of the runtime environment. This might get in the way of some security mitigations (which seem pretty weak to begin with) and some monetisation models (i.e. enabling pervasive tracking across apps), but the end result feels more "clean" and like users would expect - the app runs in a sandbox where there's no access to anything to distinguish the app from any other instance of it.
Clearly keeping this up at the network level is far harder (and some app developers will probably fall back to using the WAN IP and other factors), but perhaps there are even solutions here - perhaps TCP relay servers mix user traffic (while leaving it HTTPS-protected) to prevent services from seeing user IPs, and a virtual network interface internally in the runtime ensures apps only see an IP of 10.0.0.1.
It seems a worthy goal to try to ensuer that runtime environments are indistinguishable, at least to end cross-service ad tracking once-and-for-all. Handling it within apps probably comes down to policy - not sure any technical mitigations can prevent this while apps can remain Turing complete (as they can simply store their own identifier).
That would be premature. Nobody is in a position to know how the "extinguish" portion of the plan will turn out because it hasn't happened yet. All we can say is that the plan looks quite robust in theory and would be a significant coup for Apple if they can pull it off.
Obviously there will always be some unethical operators, but that is true of all major platforms. Apple has the benefit of top-down control and some amount of market incentive to get it right.
> For example, in the web browser ecosystem
...there is precious little to block effective fingerprinting of 99%+ of installs and little prospect of that changing.
Either there are alternative ways to track a user of an Apple device without IDFA or there are not. If there are, then it is reasonable to assume that unethical advertisers will return to using them if their access to IDFA is gated.
So, whether or not IDFA exists, the only robust way to protect users is to block apps from having access to anything about the host device that implicitly provides a unique method of identifying the user.
This is what other platforms have been trying to achieve. For example, in the web browser ecosystem, software has been restricting programmatic access to features that can be used for fingerprinting or deliberately reducing the level of detail exposed by some APIs.
With control of the entire ecosystem, why is Apple not better placed to adopt this strategy than anyone else, and whether or not Apple is technically capable of achieving the perfect result, how does introducing IDFA make any difference?