That's misleading at best (GUI windows apps that technically can be emulated from the commandline often practically cannot be--CLI tools or the registry/config-file interactions required to perform actions that are clearly exposed and well-documented in the GUI often have nonexistent or terrible documentation. In even marginally complex apps, this puts the effort required to script the functionality of the GUI on par with the effort of reverse engineering it--and that's Microsoft-authored tools and Windows functionality, which is worlds ahead of most third-party software in scriptability) and just plain false at worst (huge swaths of stuff just don't have APIs that are accessible without writing and compiling code--PowerShell and very aggressive pushes by Microsoft for WMI/CMI and WinRM more recently have only just begun to erode that).

AFAIK, the only way that you can even set a system wide environment variable without using the GUI is by using Powershell to modify the system registry.

How is it misleading at all? Hyper-V Manager for example is literally a wrapper for Powershell commands.

Virtually all Windows administration can be done entirely in Powershell.

And like I said, the literal default installation of Windows does not even include a GUI.

What do you consider the "literal default installation"?

Every Windows Server release following 2016 RTM: https://docs.microsoft.com/en-us/windows-server/get-started/...

I think we have differing terminology. I would consider this a GUI. After all, the command prompts are running in windows. You can move them with your mouse. Other utilities (like regedit) are available, and are not command line / text-only applications.

Something very, very different to everyone else, it would seem.

‘Windows’ would be an interesting name for a product that by default had none.

Ok. Can you post an image of what the screen looks like after you log in?

Probably the Nano version.

What are your criteria for a "proper operating system" that just happen to exclude the most-used desktop operating system?

This is about "Windows Server", which is an irrelevance. As indeed in "Windows Desktop" for the last decade as almost everything is now web-based.