> the original "clean, overengineered" NT design has been buried under a progressively bigger truckload of crap year upon year and is no longer as clean as it once was.

The original UNIX model has (considering the current state of GNU/Linux) similarly buried under a progressively bigger truckload of crap year upon year and is no longer as clean as it once was.

A central difference is: the NT kernel stayed rather clean (the crapload rather happened in the Windows subsystem).