I found it a bit ironic that Apple didn't require users to grant permission to its own measurement tool, "because it is engineered to not track users". I don't know the details but I am guess it is still accesses the same numeric id and "trusting" that Apple is doing the right thing behind the scenes, i.e., only storing aggregate information is still required.
Sounds perfectly reasonable. Apple only cares about the data in aggregate. They don’t need to track individual users. An advertiser, on the other hand, wants to know your age, sex, location and what you hard for breakfast.
I wouldn't be surprised if they still break down information by age, sex, and location as long as there are enough anonymous people in each group.
I would argue that this is only "perfectly reasonable" if you think anonymous aggregate logging solutions is a reasonable way to track user behavior, or if you have such trust in Apple to do the right thing, that you are willing to grant them an exception.