Sure, that's true and a pretty valid criticism of the system.
My definition of open is that Khronos doesn't restrict (as far as I know) what platforms Vulkan can be implemented on. The same cannot be said for DX12 or Metal.
DirectX 12 headers seem to now be published under the MIT license, so I don't see a real difference from a "who is allowed to implement it" perspective.
My definition of open is that Khronos doesn't restrict (as far as I know) what platforms Vulkan can be implemented on. The same cannot be said for DX12 or Metal.