What has Microsoft "Done" to AMD exactly?
DirectX 12 is for all intended purposes what the AMD Proposed DirectX 11.3 Feature Set was supposed to be., now why it was delayed as long as it was, well that likely remains an element of the Politics of the Graphics Industry … but still, keep in mind it did strictly speaking ultimately launch ahead of Vulkan (the 1.0 Standard) in it's "Game Ready" / "Public" Specification.
Ultimately the decision to make the major change to rewrite Direct3D (and DXGI) from the Ground Up, was better than the proposed Atomics (Hybrid HAL+CTM) that DirectX 11.3 would've had to have been... and wouldn't really have provided quite the same optimisation or benefits that DirectX 12 does.
This has been showcased as DirectX 11.3 and 11.4 have now been released., offering some of the improvements from DirectX 12 but still has some notable limitations.
Now beyond this, AMD has been and remains Microsoft' Primary Choice for their Console Hardware.
Xbox Scarlett will mark the 3rd Pure AMD Platform, and 4th Console (out of 5) that utilises Radeon Graphics.
There is also embedded Radeon Graphics within both HoloLens and Windows Mixed Reality Headsets.
At best, you can say that the Microsoft implementation of HDR / WCG (which frankly has been a mess since it was introduced, NVIDIA., as always simply bypass it, while AMD/ATI remain quite strict to the PlayReady 3.0 Standard; but keep in mind said Standard isn't used by most Display Manufacturers outside of "Select" Modes)
Or you could say the DirectX Ray (DXR) API, is maybe AMD "Unfriendly" given only NVIDIA RTX supports it with Native Drivers., but honestly this is more AMD making a point rather than Microsoft deliberately siding with NVIDIA on said Technology.
Keep in mind it still isn't exactly "Plug-and-Play" on RTX 20-Series Hardware either., you still realistically need the RTX Gameworks SDK to really make any meaningful usage of it without heavily falling back onto the CPU.
AMD on the other hand, could of course integrate Radeon Rays as part of their Driver Layer for DXR (as the two are almost indistinguishable in terms of Functionality and Features) but this is something that AMD themselves decided against... as not only does it appear that they would prefer to support it with Dedicated Hardware (Radeon Next-Gen, not Navi) but more importantly,. even if they were to implement their own Driver Support; you'd essentially be limited to RX Vega 56 / 64 or Radeon VII as the Hardware capable of providing the performance necessary for "Gaming" Real-Time.
And AMD have stated that they'd prefer to wait until their ENTIRE Product Stack (from Entry Level to Prosumer) is capable of delivering "Game Ready" Performance.
This is something that not even the RTX 20-Series with Dedicated Hardware can boast just yet., and further to the point we're talking about a heavily Hybridised Solution, with minimal DXR Features used to attain respectable performance.
At present RTX (DXR) is realistically only any use for Technical Demonstrations, or Content Creation Pipelines that don't require 30FPS+ and instead just need a Semi-RT Draft Quality for Ray/Path Traced Scenes as well as heavily accelerated Production Quality.
Neither Vulkan nor DirectX 12 strictly speaking "Favour" or "Disadvantage" AMD... still bare in mind that AMD Hardware typically more strictly adheres to DirectX Standards rather than Khronos Standards.
We're in an odd position right now where, they're basically supporting both almost as well as each other... but that more likely has more to do with the fact that Mantle and OpenCL were used as the base for Vulkan., but you can expect as the two evolve they will (like ATI and OpenGL) diverge.
