Apple's change wasn't a feature expansion, it was a limitation and clarification of how the device identifier should be used. Originally, Apple allowed all apps

Apple's change wasn't a feature expansion, it was a limitation and clarification of how the device identifier should be used. Originally, Apple allowed all apps to access a common unique identifier tied to each device. As a developer, it's incredibly useful to identify devices -- but it also had significant privacy implications, so they deprecated this common identifier. Instead, Apple provided two alternatives: * A vendor-specific identifier that is shared among all apps created with the same vendor prefix (essentially, coming from the same company). This provides what most devs need for identifying users within their apps and even across apps. * An advertising identifier that is shared across all apps. This is intended for tracking, but Apple also provides a couple privacy protections for users: (a) users can set a flag asking apps not to perform tracking with this identifier, and (b) users can reset this identifier whenever they want –- the equivalent to clearing cookies.