[vbezhenar]

It's pretty simple chain:

1. Most consumers using Windows. That might not be the case in USA, but definitely the case in the most of the world.

2. To develop for a platform, primary choice would be platform creator recommendation. In this case it's obviously .NET from Microsoft Visual Studio. It contains extensive UI libraries and components.

There are alternatives, of course, you can use Qt or Electron or just web app. But you would need a good reason to move from the primary path. For many projects there's no good reason, so you naturally using .NET to write GUI applications for Windows.

3. To develop .NET GUI applications, you need Windows. Any other option is inferior.

That was the case 10-20 years ago. So plenty of projects were created and plenty of developers were taught .NET and Windows.

Today web apps are more popular. But .NET provides excellent support to create web apps, so there's no reason to switch from Windows.

That's why many professional developers use C# even today.

Of course different people might move different paths. But I think for majority that's the way. .NET GUI frameworks and may be Sharepoint created huge number of Windows developers.

[neonsunset]

Today, there is no reason to use Windows specifically when developing back-end or GUI (unless you're stuck with WPF and co) applications in .NET.

Though the argument makes for a convenient straw-man since it used to be true until 2016.

[prmoustache]

I was just following the running gag, but thanks anyway. I did a bit of C# when, as a sysadmin, I was asked to do some kind of frontend that would hide the pocket pc interface so that employees in an hospital can use those pocket PC to order menus for the patients and not end up using them to browse shit or install unwanted apps.

Security by obscurity in all its glory but they used to do the same with a very easily escapable panel replacing the default windows shell in Win95 and Win98. :)