It's a simple fact that Direct3D features are drafted many years ahead (3-5 years), otherwise there would be no way to add the right set of features to the GPUs in time. Direct3D 12 was like all previous versions drafted years ahead, anyone believing anything else is ignorant.
You might remember tessellation as the big feature of Direct3D 11, but did you know it was actually planned for Direct3D 10? Both AMD and Nvidia made their hardware implementations (
example), AMD provided Direct3D extensions, and both provided OpenGL extensions. For some reason this was left out of the final spec, and a more mature version arrived instead in Direct3D 11.