It may be funny but it may be a way to support certain older games/applications that don't run well on Windows 10. For example in order to run Dracula 3 on Windows 10 one has to use the Wine implementation of Direct3D: https://fdossena.com/?p=wined3d/index.frag

Or you can just build wine on Windows for Windows. I've done that long time ago for Yuri's Revenge.

I've actually tried to run HeidiSQL through Wine on Windows and I succeeded.

The tricky part was the X11 server. X.org doesn't seem to work on the Linux subsystem, but there are a few X11 servers for Windows. If you install one of them, you can run Linux GUI programs.

Xorg works in WSL, it just doesn't have any backing graphics driver to actually render anything. But if you install XRDP, you can connect to your Linux desktop using the usual Windows remote desktop client.

But yes, there are better options. You can run Xming or other X server and configure it yourself. Or you can buy X410 in the app store, and then the only configuration needed is DISPLAY=:0 in your shell.

https://token2shell.com/x410/

I guess that would be helpful if you wanted to run 16 bit software on 64 bit Windows.

There's NXVDM which is a port of the i860/Alpha/MIPS/PPC NTVDM compiled for AMD64. https://sourceforge.net/projects/nxvdm/

Few use cases I can think of:

Testing across multiple .net frameworks without containers or virtual machines.

It's a lot faster to initiate an app inside wine on Linux then start up a VM and launch it on Windows. I think it's even faster than containers on Windows but don't have any data to back it up.

Lastly, for sandboxing applications (not a great security layer of course, but safer than running natively) so they don't pollute the registry or access sensitive files.

Wondering if it's possible to play dx12 games on older versions of Windows that don't officially support it.

Funnily enough, there was an article about malware doing exactly this for AV evasion some time last year. Existing behavioral analysis wouldn't be effective since they were looking at Linux syscalls.

Well, you can run Wine on Windows (which makes sense if you think about it).

IIRC you can run wine on cygwin, so I wouldn't be terribly surprised if wine on WSL worked.

Also Docker for Windows can run Windows and Linux containers.

Would be a strong contender for "turtles all the way down" of the year.

I'd suggest running an Amiga emulator. There was a Mac "emulator" for Amiga that required Mac ROMs to function.

Sadly, the Apple II emulator for Macs was real hardware.