Dave Cutler's skills aside, Unix predates Windows by decades, and to anyone remotely familiar with kernel development it is clear that the sheer quantity and complexity of subsystems stem from the fact that nobody but Microsoft can actually see, modify, and redistribute Windows' source code.
Unless you can actually say "here's why Windows is qualitatively better" and point out specific tasks Windows does better, I'll just point you to the fact that the internet infrastructure and most of the servers on it, along with every Apple desktop and pretty much every mobile device, run Unix.
I wonder how much of the internet infrastructure would run Unix if free (as in beer) clones like *BSD and GNU/Linux did not exist in first place.
How much internet infrastructure would run actually Unix if ISPs had to choose between Aix, HP-UX, Solaris, Digital UX, Tru64 and Windows licenses?
Free is always more valued than quality.
And of course this worked in reverse, when Netscape released their commercial webserver Microsoft rushed to give away IIS.
Also, on an high performance poll/epoll/kevent based system you only need to poll cold fds, while you can do speculative direct read/writes to hot fds, so no need for extra syscalls in the fast case.
That doesn't mean that completion notification doesn't have its advantages, especially when coupled with NT builtin auto-sizing thread pool, but it is not strictly better.
(FYI, I've read the "internals" book for a relatively old version of Windows, along with plenty of books about attacking the Windows kernel through its huge attack surface that exists to accommodate various needs of various software vendors...)
Now at one point, way in the past, NT was far above Linux, and some Linux fanboys existed that did not even knew what they were talking about, yet had strong opinions of superiority about the kernel they used. Now we are ironically in the opposite situation: Linux has basically caught up on all the things that matters (preemptive kernel, stability, versatility, scalability) and then quickly overtook NT, yet some people like to talk endlessly about the supposed architectural superiority of NT, that did not provide anything concrete in the real world in the long term and widely used, and that MS had to work around and/or redo with an other approach (while keeping vestigial of all the old ones) to do all its modern stuff.
What kernel hackers know to do, is to detect problem in architecture that look neat on paper. Brillant ones are able to anticipate. I don't even have to: history has shown were NT has been hold back by its original design.
