Maintaining the integrity of the hardware maintenance chain:
MacRumors: In 2013, Apple is said to have discovered a highly sophisticated fraud scheme in which organized thieves would buy or steal iPhones, remove valuable components like the processor or logic board, swap in fake components, and return the “broken” iPhones to receive replacements they could resell.
I’ve just realised that that supply chain integrity happens before and after the initial sale. Post-sale repair operations can be compromised and this may be why the post-sale repair is being restricted by Apple.
Appleinsider : In a move that essentially puts the kibosh on third-party repairs, Apple with its latest Macs has instituted a T2 security chip-related feature that disables a host machine unless specialized diagnostics software is used when replacing hardware.
Link: Apple Said to Have ‘Dramatically Reduced’ Multi-Billion-Dollar iPhone Repair Fraud in China – Mac Rumors – https://www.macrumors.com/2018/10/09/apple-dramatically-reduces-iphone-fraud-in-china/
Link: Apple diagnostics software blocks third-party repairs of 2018 MacBook Pro and iMac Pro – https://appleinsider.com/articles/18/10/04/apple-diagnostics-software-blocks-third-party-repairs-of-2018-macbook-pro-and-imac-pro