Did you watch the video in the OP article? They don't allow certified third parties to make all repairs. Specifically, not to the iMac Pro.
So what if the unqualified shops charge less? That's free-market. Compete, either on price or on service. If third party shops offer a 30 day warranty on repairs, the first-party ones can offer a 90 day warranty. Or they can offer a faster turnaround time. If the unqualified shops do as good of a job as the qualified ones, doesn't that just prove that the qualification is just BS to begin with?
The video isn't true.
"At one point in the video, after Apple itself suggested that the venue talk to a third-party shop, the group was told that training for the repair for the iMac Pro wasn't available. This is false, and likely used by the shop to dodge the repair. Training materials have been available since before the iMac Pro launched, with some components able to be ordered in January, with the rest ready in early March."