I guess since this is emulating the device instead of just passing the commands to vulkan it is easier to do DX11, but I could be wrong about this particular implementation.
I could be remembering this incorrectly, but that's the impression I remember.
Honestly if you are creating games, with the rise of Proton and vkd3d, there is seemingly less need to target Vulkan today than ever before. Just target x86_64 Windows with DirectX11 or DirectX12 and you will even get Linux support (and some day, probably macOS) "for free". That's just for games, though.