> Optimization and bug hunting makes supporting multiple graphics api's a pain.
The problems usually lurk in the graphics drivers, and not in the 3D API layer (e.g. optimization and bug hunting isn't much difference even when your code only supports a single API, and especially Vulkan drivers from different vendors may behave wildly differently on Windows, at least compared to D3D).
> I can see PC game developers seriously considering Vulkan over directx
Lol. That train has left the station long ago (around the time when Stadia was shut down, Vulkan saw a small uptick because of Stadia, but that soon fizzled out). Games need to support multiple 3D APIs anyway once they release on consoles. One or two more for the PC and Mac version doesn't make much of a difference (and most games are built on top of an off-the-shelf-engine anyway).
You may note that I specifically said "PC game developers" Your whole but consoles argument, completely misses the mark.
Exactly, and having a Vulkan-only codebase won't make that problem go away. And IME it's much more likely to encounter vendor-specific driver issues on Windows Vulkan drivers than for D3D drivers.
Vulkan drivers on Linux are in a much better shape because they are centralized under the MESA project (except NVIDIA's drivers, which also have significant behaviour differences to the MESA drivers, at least in the window system glue).
> You may note that I specifically said "PC game developers" Your whole but consoles argument, completely misses the mark.
Why should a game developer support the tiny Mac market, but ignore the much bigger game console market though? From a business perspective, Mac support simply doesn't make sense, it's too much hassle for too little return (and the hassle isn't about the different 3D API, Metal is actually one of the best parts of the whole Apple developer ecosystem).
Mesa is largely an Umbrella. While some of the code is shared by in large, AMD works on radv, intel works on vulkan-intel and of course Nvidia work's on its own proprietary driver rather then very limited NVK.
Many games are first released on PC and only ported if they get big enough. So there are no considerations for cross-platform support in the original development.