Apple puts effort into making you go to them for repair parts. Any deterrence against thieves is simply a fringe benefit. Don't credit them for something that isn't actually their goal.
I think it is pretty clearly a goal - when you create marketing campaigns around an aspect of your product (and Apple has around this sort of security), delivering on your promises is clearly a goal.
I wouldn’t be surprised if the original impetus for this variety of security was a prompt like “what are some objectives that support us creating vendor lock in” - that’s how organizations end up with multiple interconnected objectives
The purpose of marketing is to bend the truth to something that is going to attract customers. It doesn't have anything to do with the actual goals of the company.
When buying my child her first iPhone we went through so many used devices at the local phone store which had all been refurbished or repaired using sub standard 3rd party screens.
Being able to see Apple’s warning on the iPhone 11 and up "Unable to verify this iPhone has a genuine Apple display” meant we were able to find a phone which was still stock.
I’m a big proponent of the right to repair but in this case Apple’s repair deterrence feature had a big benefit for us.