"because they've been crushed by the enormous efforts of open source"
As opposed to their own ineptitude (e.g. Vista and Windows 8) or the changing of the guard from original founders?
I'm certain open source played a role, but I suspect a secondary one. Heck, if post XP Windows didn't suck so much, I and my parents (who nowadays run what I build them) would be using it instead of Linux for our desktops.
Vista and Windows 8 aren't the problem. Lack of presence on servers and mobile devices is the problem -- those are the two key spaces where OSS platforms have won out.
Linux is still not a significant player on desktops. Microsoft is still completely dominating that space.
Nobody in a ten mile radius of me gives a crap about what is running on servers or phones. Most of them do not recognize an Android smartphone as a legitimate computer. They do not know what a CPU is, they do not know what a hard drive is, and they think their monitor on the desk is the computer and the tower in the closet is the "CPU".
Windows has the mindshare of the masses. When many upper-middle class white Americans want to write a document, they can only fathom word. When they want to do a spreadsheet, they can only fathom Excel. When they want to draw, they can only fathom Photoshop.
It isn't about options or features or anything, I'm talking about the super majority of people who cannot any longer comprehend the existence of anything but what they know - where being presented with Linux destroys their world view. They talk about OSX like its an easy bake oven rather than another computer, or as if its another desktop UI for Windows that also runs Office.
Which is why Microsofts open source efforts are pretty much all on the developer end. They know their userbase is completely ignorant to everything just the way they intended, and it would take years of retraining to push the public conscience away from the mindset that Microsoft Windows is the personal computer, and everything else is some gadget.
Mobile devices I firmly ascribe to ineptitude, and can supply some 2nd and 3rd hand details I've read about.
Servers are more complicated. In the mid-90s Windows NT started dropping in quality, and the much older decision to have mandatory file locking resulted in situations where creating a server with a major MS server application could require ~ 20 reboots. And many more bug and security fixes require reboots than they do on UNIX(TM) based/inspired platforms.
Then one could argue ineptitude in marketing when Microsoft didn't cut deals that could have made their software competitive for mass installations. I really wonder about that, because so many of these need source, but it's "a path not traveled", except internally with Azure.
As opposed to their own ineptitude (e.g. Vista and Windows 8) or the changing of the guard from original founders?
I'm certain open source played a role, but I suspect a secondary one. Heck, if post XP Windows didn't suck so much, I and my parents (who nowadays run what I build them) would be using it instead of Linux for our desktops.