Point is this is Unreal engine, not specific ARK work, and they specifically say it's a "drivers and the hardware vendors" issue, and not something on their end.
So the bad performance is not the code, it's the drivers and hardware that are NOWHERE close to all the hype that preceded this. Especially the whole myth of "better performance on current hardware".
Yet, there are some games that perform just fine using DX12 with current hardware. Wait for more games to come out with DX12, especially fully released games, before making judgement calls on the drivers and hardware...