For me, it's not about FOSS per se, more about the development environment that comes with it; a parent comment even mentioned a hackintosh. It's just that a Windows environment is so radically different from everything else out there that it makes it pretty impossible to realistically conduct work when all the tools are made for OSX and GNU/Linux.

I'm only addressing Microsoft with my comment because that's the topic of conversation here. Also, because they're specifically positioning themselves to convert Mac users, and IMO a notable portion of these users are developers who need the POSIX-like ecosystem.