> It's strange to me that Apple would choose to disadvantage themselves

How exactly are they disadvantaging themselves? Perhaps expand on that opinion a bit, and the data/assumptions you're making in forming it.

My naive assumption is that they're going to do what everyone is doing: make tooling that lets you swap in any model.

I don't think it's fair to assume incompetence, on their part. I think it's much safer to assume they're doing what's best for them, and it's very clear to them what's best (money, support, etc).