I'm not quite sure what kind of metric you're referring to, but Apple is simply centralizing data collection of its ecosystems. The incentive is more comfortable service interaction and less entities receiving information about you.
On the other hand, Apple is tightening its control over its own ecosystems as every interaction has to go through them. Moreover, they're inhibiting anonymous usage of services as more and more things required direct or indirect verification of the user. This entices the market to normalize the demand for unique virtual identities.
