This is a common misconception. Microsoft is a little insane about backward compatibility. You can target versions of Windows with a single binary from the latest all the way back to unsupported OS's like XP. There are lot's of companies that take advantage of this. It's one of the reasons why MS has so much trouble moving app developers to the new hotness, even if it's safer, faster, or whatever. Because of that the new hotness doesn't get enough traction to support continued development and they sunset it early which draws even more ire from people.