I know right? just imagine if WSL2 was supporting Linux GUI apps running on Windows, we wouldn't be needed a Linux distro install in the first place, Oh wait.

If you're running Linux for application compatibility, I don't think you understand why people use Linux. (Although yes, if you want NT and only use Linux to run apps that don't work on raw NT, WSL1/2 are excellent)

At least for the desktop applications I'm developing, it is straight-forward to test them on Windows and Mac because they have the consistent underlying APIs that allow this.

Linux distros however are still moving targets and there's no common stack apart from the kernel which is predictable to test against. This is why its hard for some maintainers to reproduce an issue a user has due to possibly apt-get, rpm, install package or use snap, flatpak or appimage and the app starts to break.

Not a problem for CLI apps, but a problem for testing desktop apps on Linux. Perhaps you want your favourite app being fully supported and tested on your Linux distro of choice. If I know my app works and is tested on Linux distro A,B,C,etc I can confidently target a wider range of Linux users. At least that's how I increase my "Linux userbase".

The fragmentation on this however is another story.

Indeed you can run Linux GUI apps on WSL. You just need to install one of the X Window servers that are available for Windows.

People were saying that without the /s in the 90s though.