Ah, yes, Windows NT.
I remember how this little operating system with a kernel invented by a Finnish dude and with no real corporate back almost completelly ate their market share in the server space back in the day (not that they've had a significant server market for long in between the end of the era of corporate Unixes like SunOS and the beginning of the era of Linux).
I actual did server-side development and just about every company I worked for in 2 decades and 3 countries had masses of Linux servers and if that much a handful of Windows servers, and that included all sized of company, from small ones to massive corporate behemoths - Linux was simple the best way to get the most use and performance out of your server hardware.
Whilst I haven't been doing server side stuff for a few years, I'm actually surprised they still have any server market at all, since the only upside their server solutions have over Linux is perfect integration with their Desktop OS whilst all the rest are downsides.
I guess that they have some market share because basically their servers serve as glue between instances of to their Desktop OS in a network because of using closed protocols (i.e. a forced dependency on the desktop market rather than superior quality) whilst for any kind of generic computing they're an inferior solution to even a free OS.