You're missing my point. What I'm saying is that, as things currently stand, all of the CPUs that Apple ships in products are functionally identical -- all of them share the same root of trust in ROM (afaik?), and it would take a significant effort for Apple to produce devices which differ from that specification.

> How? Most people will stick with defaults

By having an attacker deliver a system to a user with a custom root of trust -- which could mean anything from a state-sponsored attacker to an abusive partner.