Now more than ever the operating system and even the type of computer you use is less important. Granted desktop apps are more usually powerful than mobile or web apps, but it depends on the context in which you need access to the app.
The only things keeping me and probably others on Windows, I believe is the following:
Ease of repair
If something goes wrong, most of the time a reboot will fix any issue in Windows. If something goes wrong on a Linux box, be prepared to ask questions on a forum.
Cheap hardware (this works for Linux also)
It’s cheaper to use a custom built PC or some Dell/HP machine you got for a few hundred bucks than a Mac.
It runs Adobe apps (so does Mac)
This is something Linux can’t do unless you are using a Virtual Machine or WINE.
Familiarity (this isn’t an issue for me as I use a Mac at work)
Most people don’t want to relearn how to use a computer. Even though Microsoft changes the names of things and where settings are located, everything else is very similar. Switching to a Mac isn’t too hard but their are enough differences to make the switch something most people don’t want to do. Linux is simple if all you do is surf the web and check email, but beyond that it gets pretty complicated. But you could argue general users don’t want high security, just enough to get by.
There’s times I think of switching to Linux, but then I think, “What if something goes wrong, I don’t want to troubleshoot it” and “It won’t run Photoshop”. Switching to Apple means hardware costs more, for example an iMac with a built in monitor (I have a big monitor already) or a $2000+ Mac Pro. Not to mention less choices in free applications, although its not as big an issue as it was years ago. Sometimes you’ll find a app that does what you want and costs a few bucks, but you know there is a free app that does the same thing for Windows.