Earlier quoted context omitted.
QnX did that in ... 1983.
I'm not sure comparing an RTOS to a really old school monolithic kernal is fair. Windows wasn't designed to be like QnX. I really wish QnX was open source though and had a thriving community behind it.
Whether or not Windows as designed to be like QnX is immaterial, the question is what would be the better OS to serve as the engine behind a computer interacting with its users and my vote definitely goes to a real time operating system using a micro kernel. Because in my opinion that's by far the best match for that workload.
Stability, speed of interaction driver isolation and so on are much much better when using something like QnX vs a monolith. And a GUI is a real time affair.