So let me repeat it: 2 major DX12 features are supported by Intel and NVIDIA HW, but not by AMD. Giving the limited resources AMD has this is hardly surprising. Let's hope Vega fixes this problem, even though after seeing how little was delivered in terms of new features on Polaris I am not holding my breath.
AMD have integrated what they call their "Primative Discard Accelerator" into Polaris architecture. It has not been talked much about yet, but we can be sure it will be enabled should Conservative Rasterization be used.