MS supporting Vulkan instead of DX would be shooting at their own feet. Makes 0 sense to them.
Same as supporting standard HTML instead of ActiveX and Silverlight? If not using lock-in is shooting in one's own feet, you have some strange notion of what's normal.
Exactly same thing here. They used DX to lock 3D graphics into their platforms.
Whether they lost deservedly or not, lock-in is always a crooked practice.
See my other comment[1], that with DX12, it's more clear that MS are doing it for the sake of lock-in. Problem with it - it doesn't compete on merits on Xbox for instance. Because it's the only thing supported there.