OpenGL AZDO is conceptually very near to Vulkan and DX12. Few years ago, I had an impression that Nvidia wanted to go this route, instead of Vulkan, if for noth

OpenGL AZDO is conceptually very near to Vulkan and DX12. Few years ago, I had an impression that Nvidia wanted to go this route, instead of Vulkan, if for nothing else then just to make advantage of their investment into OpenGL. However, AZDO is unusable on macOS; the OpenGL on macOS is too limited to support it. Khronos with OpenGL 4.6 made another step towards Vulkan: SPIR-V shaders. If Apple implemented 4.6, they could go all they way and implement Vulkan too. Apple, while they released the Metal 1 first, it was quite limited and there were reasons why the release was iOS only. When they came with Metal 2, which could compete with Vulkan, Vulkan was out for a year already. So basically they rushed to come with API, that would be exclusive to their platform and lock their developers in. There's no other use for Metal today.