I'm thinking that one reason Microsoft won was because of superior developer tools. I admin'd a small Netware 4.x machine back then and I couldn't even tell you what was needed to write an NLM.
Thank you for that reminder. The NLM platform was a fragile architecture.[1] In contrast, both IBM OS/2 and Windows NT of that time period had superior architecture (memory protection, separation of kernel-vs-user address space) for complex applications.
And to add to the other commenter about ease of dev tools -- it definitely was easier to use Visual Basic 3.0 and deploy the app on NT rather than use Netware's NLM SDK that required the C programming language. Even though VB was marketed as a tool for desktop apps, it didn't stop Microsoft shops from deploying VB apps on the server side.
[1]https://en.wikipedia.org/wiki/NetWare_Loadable_Module#Progra...