Not sure how this impacts theory of neglect.
Is it correct that the best folks from any given team at Apple are assigned to new, big initiatives?
Yes, they should. The vast majority of QA should be automated unit and integration tests.
> QA is unnecessary
This is objectively false. Even if you perform 99.999% of all QA in an automated way, you're still going to miss those edge cases, like the infamous daily kernel panics due to buggy support for external USB-c displays that only real humans testing your product in the real world with 3rd-party devices can find. QA is still extremely important, and when companies like Apple neglect it, they end up shipping buggy and disappointing products.
1. mac os has been buggy for quite a few releases already
2. outside of drivers and apps, ios and macos are basically the same kernel and userspace/libraries, so there isnt much to port
mac os at large has a quality problem. I have gotten more kernel panics on my personal and work laptops in the last 6 months than I have on my windows machines in the past 5 years.