Hardware aside, I honestly don't understand why anyone who writes software would write software on a closed source OS.

The excuse I most often hear is that "they have better things to do than mess with Linux configuration". That's a healthy viewpoint, for say, a scientist or an artist. But if a software developer does not like hacking around with software they are probably in the wrong career. In my opinion, giving up control over your most important tools for a bit of short term convenience is bad economics.