

Exactly, bitlocker or disk encryption prevents this from working and because you need some means of editing the file system outside of the user permissions, also physical access is required. At this point your are pretty much authorized to unplug the box and walk out of there with it (even if your not supposed to).
Also, ask when Rome fell, historians wont agree on any specific date. They were never the top of the town afterwards, but the fall was more of a gradual multi-century tumble punctuated by hitting every rock on the way down.