Why Linux is not subsystem for Windows?

These packages were part of Microsoft’s late-1990s/early-2000s efforts to elbow its way into established networking environments. Conversely, the name isn’t “Linux Subsystem for Windows” because Microsoft hasn’t ever used “for Windows” as a suffix to a component name in Windows.

How does Windows Subsystem for Linux?

The Windows Subsystem for Linux lets developers run a GNU/Linux environment — including most command-line tools, utilities, and applications — directly on Windows, unmodified, without the overhead of a traditional virtual machine or dualboot setup.