Apple's decision gave occasion to reiterate that electronics manufacturers complicate the fixation devices in order to strictly control the fix market and encourage the purchase of new devices. For the iMac Pro, the diagnostics tests only applies to the desktop's logic board and flash storage.
As far as the MacBook Pro, this affects instances where the parts to be replaced cover its display assembly, logic board, top case (i.e. keyboard, touchpad, and internal housing) and Touch ID. And it seems unlikely Apple will stop at just these two products, since Apple will probably ship many (if not all) future Macs with a T2 chip.
Citing internal documents distributed to Apple's Authorized Service Providers, the original reports said that Apple is using a new Service Toolkit 2 software lock.
The MacRumors report claims that the new T2 chip integrates several components of the new MacBook Pro and iMac Pro models including the system management controller, image signal processor, audio controller, and SSD controller.
This software is created to confirm that all of the computers' components are working properly together, but only works when the computer is connected to Apple's cloud servers for repairs and service that requires a login sent direct from Apple: the Global Service Exchange (GSX). This shouldn't come as a surprise, as Apple is actively lobbying against the movement, according to NY state public lobbying records that Motherboard has sourced. "Not everyone lives near an Apple Store or authorized service provider, so it may also make fix much less accessible for people living in underserved areas".
People who have Apple devices are fully aware that the best way to resolve problems on their machines is to have them checked by authorized Apple technicians.
What do you think about this? This essentially bars third-party repairs, and would also make it hard to fix said machines once they are classified as vintage machines.