Comment by rzzzt
2 years ago
Historically, the US Government. NIST mandated that only those operating systems should be used where existing applications can easily be ported to and fro, and POSIX compliant OS-s tick all the boxes. Windows NT got its POSIX subsystem for this reason: https://en.wikipedia.org/wiki/Microsoft_POSIX_subsystem
Which was hobbled to the point of uselessness are purely a box ticking exercise.