Do you really believe that lie, or you just repeating something you heard some muttonhead blubber out on some leet bord?
Windows has never been "nothing more than a graphical interface for dos". From inception, it was a cooperative multitasker (you know, like the notorious Crapentosh used for lo those many years, up until just recently). The early versions did indeed run on top of DOS, and used DOS interrupts to handle various I/O tasks.
Beginning with Win95, Windows was a preemptive multitasker (like unix). It used DOS as nothing more than a bootstrap loader, unless you needed to use "legacy" drivers (16 bit).
NT has been entirely "DOSless" from day one.