https://developer.apple.com/documentation/devicecheck/access...
https://developer.apple.com/documentation/devicecheck/access...
This isn't a feature that is actually costing them sales but a lack of DRM/etc affects what apps will be in their store.
That makes some people feel really secure, like the company is a loving parent, although companies don't love. They decide what is profitable and what is not.
Service providers need to ban people sometimes. This includes people who are savvy enough to know how to delete and reinstall an app to clear its settings. Never permanently banning anyone simply isn't a thing that's happening.
If Apple didn't provide DeviceCheck, or something similar to it, service providers would use some other means of deterring abuse. There's a couple directions they can go in, but they're all generally worse for users (e.g. using invasive tracking, requiring users to pay for service, etc). DeviceCheck is about the least invasive way I can imagine this being implemented.
Does resetting your iPhone (Erase All Content and Settings) clear out data like that?
Does doing a restore from backup put that data back on your iPhone?
I.e. they could persist even if the device were bit-for-bit reset to factory state.