In order for the device to display the content on the screen, some part of the device has to have access to the plaintext. That part of the device is controlled by Microsoft -- it's their DRM system, they wrote that code and have the keys to update it -- so they inherently have access to it. Saying "that part is outside the scope of the DRM" is just defining your way around the fact that they can still do it.
Or to put it another way, if some court orders Microsoft to extract some DRM-protected content, what do you think happens?
To really delve into the technical side of things: I’m fairly certain that large parts of Windows, especially when it comes to DRM, rely on third-party technologies, components that Microsoft licenses and integrates but doesn't necessarily have full visibility into or control over. That could very well include parts of the DRM stack itself.
So while Microsoft controls the platform, that doesn’t automatically mean they can trivially extract plaintext content from DRMed streams, especially not without compromising the integrity of systems they themselves may not fully own.
In order for the device to display the content on the screen, some part of the device has to have access to the plaintext. That part of the device is controlled by Microsoft -- it's their DRM system, they wrote that code and have the keys to update it -- so they inherently have access to it. Saying "that part is outside the scope of the DRM" is just defining your way around the fact that they can still do it.
Or to put it another way, if some court orders Microsoft to extract some DRM-protected content, what do you think happens?