It's not just Apple that's shipping AMD and Intel chips with a special security coprocessor (ME/PSP) embedded in the CPU that only boots signed, unmodifiable code: everyone in that marketshare table is doing so.

What OS does the main CPU run? Usually the one from Microsoft, the vendor with specific state-of-the-art expertise in locking down the platforms on which they operate stores (xbox).

Apple is simply ahead of the curve here; Microsoft (and the entirety of the PC market they run on) will get there soon enough.

I hope you're right and I'm totally wrong, but everything I see with regards to platform stores, DRM, and "cryptographic integrity of software" as it's termed leads me to believe that in a relatively short period of time (10 years, +/-5) basically nothing cheap and performant off the shelf will run open OSes or common software without significant difficulty.