Microsoft claim to embrace #OpenSource now:
https://redmondmag.com/articles/2018/09/17/microsoft-outlines-open-source-shift.aspx
So why don't they liberate the source code for Windows and Office under free licenses? I suspect it's because they are embarrassed to let the world's programmers audit the paper machet of patched patches they've been selling as "professional" software all these years.