You can run Unix processes on Windows 7 and the others with MSYS or Cygwin or on Windows 10 using the Microsoft-provided Linux compatibility layer.
Virtually all Windows PCs have a Browser installed and running. Most users know how to open and operate a Browser.
Of course it's kind of redundant for everything to be reimplemented into the browser, things that should be implemented and used on a OS level, but I think it's a testament of the shortcomings of the UX design or even more fundamental paradigms of personal computing.
I have never had any trouble running either MSYS2 or Cygwin on Windows computers even when the amount of privileges given to my account has been very low.
WSL (and flinux) enable unmodified linux binaries to be run on Windows. WSL handles this at the kernel level, while flinux uses a higher level BCT.
cygwin has another purpose: It requires everything to be built from source, linking against one or more native Windows libraries (most notably cygwin1) that emulate POSIX. In short: cygwin's goal isn't to run unix programs whatsoever, it just provides Windows applications with an interface to use emulated POSIX calls - which is awesome, too.
Since WSL supports binaries at the kernel, performance is much greater for features where cygwin would have to emulate a completely different paradigm (like fork).
So while cygwin is pretty useful for a quick and usually dirty porting of unix programs to Windows, and is even frequently used to emulate(!) a unix environment, WSL can run any linux environment of your choice (the standard being ubuntu) natively.