Before that, Administrator was the same as unix root: A person capable to administer the system for all other users.
But the average end user was not interested or capable to do the job, the computer was now personal so there were no other users, and driver manufacturers were simply not good at their job. Additionally, DRM implies you're not allowed to have full ownership of a machine anymore.
Microsoft, sick of receiving the misery of other people's incompetence and smelling DRM dollars, hollowed out Administrator. They kept the account name, as power users would rebel otherwise, but a new layer on top was created.
The almost reached conclusion: If you force it hard enough, you can gain system and kernel access, but secure boot will make sure you lose DRM at that point.
An exploit like this is why I still can say: almost.