[JonathonW]

moricons.dll (and a lot of the stuff you'll find in shell32.dll and elsewhere) is a compatibility relic; those icons are no longer used by Windows itself. There are still some lingering old icons in the UI, though.

Also, many of the DOS applications with icons in moricons.dll probably still run in 32-bit Windows 10. NTVDM and DOS application support don't exist in 64-bit Windows, but they're still alive and well in 32-bit Windows (albeit an optional install, because MS would really rather people not still be using DOS applications in 2021).