It is half-responsible, but MS did the necessary thing to achieve their capability to independently update the OS (and deliver it as binaries, instead of lettin

It is half-responsible, but MS did the necessary thing to achieve their capability to independently update the OS (and deliver it as binaries, instead of letting phone vendors built it from source, which MS do not want to distribute to anybody): they specified a common plateforme for ARM phones, that is, IIRC, basically ARM + ACPI. Then they mandated secure boot with keys that cannot be controlled by the user, so that other systems can not leverage the platform on W10M hw :p . (That's in the spirit of what BG wanted for ACPI: something somehow incompatible with other OSes -- MS eventually managed to do this with a sidestep, but well, this did not really help their market share :P )