This had the advantage that the underlying OS base would no longer need maintaining by Microsoft, and all their coding efforts could be allocated to the Windows GUI, thus permitting Windows versions to be released far more often than every 5 years as was the case back then.
Being full of Softies, the crowd on Mini-Microsoft dismissed my suggestion out of hand, it being sacrilege of course to even think of marrying the 'upstart' Linux with the 'sacred' Windows code.
Naturally, today I am smiling to myself that MSFT could have taken my idea and run with it, but were too hidebound to do so and have lost 10 years in the process.