That insane decision has been made deliberately to make competitors incompatible.
Unless you want to claim the Unix developers deliberately chose the slash as a path separator to be incompatible with TOPS-10. That could be.
[0] http://www.os2museum.com/wp/why-does-windows-really-use-back...
Not inconceivable. After all Windows is called w32 in Emacs not win32 as is common everywhere else because RMS couldn’t bear to think “win” in association with MS!