Not true. Since about Windows XP, microsoft has severely reduced the msdos capabilities of each iteration.
To be exact: in the Windows NT branch, DOS has always run in a virtual machine, where certain instructions were emulated for obvious reasons (DOS applications would just hook directly into timer interrupts and such, and write directly to hardware I/O ports to reprogram certain hardware, which would destabilize the whole system). It's a sort of sandbox to keep DOS applications from messing up the system.
The other versions of Windows (1 through 3, 9x/ME) were essentially DOS applications themselves (albeit that the DOS version underneath was adapted to Windows since 95).
Since Windows XP, regular consumers also got the NT branch of Windows, and they 'suddenly' found out that DOS was no longer the DOS they knew... but nothing special for people who'd been running NT since day 1.
The advantage was obviously that the entire system was much more stable.
In the 64-bit versions of Windows, this 16-bit VM no longer exists at all (limitation of 64-bit mode), so it is COMPLETELY impossible to run DOS or 16-bit Windows applications...
With one exception: DOSBOX. This emulates a complete 16-bit x86 system from within a 32-bit Windows application, so this works on 64-bit systems as well.