> An exception that doesn't change the rule, where are the Vulkan extensions for DirectX neural shaders, and RTX kit?

DirectX "neural shaders" is literately the VK_NV_cooperative_vector extension I mentioned previously, which is actually easier to use in Vulkan at the moment since you don't need a custom prelease version of DXC. Same for all the RTX kit stuff, e.g. https://github.com/NVIDIA-RTX/RTXGI has both VK and DX12 support.

And how does that prove that NVidia has not designed that together with Microsoft first in DirectX prototype?

Additionally, naturally Intel and AMD will come up with their extensions, if ever, followed by a Khronos common one. Not counting mobile units into this extension frenzy.

So then we will have the pleasure to chose between four extensions for a feature, depending on the card's vendor, with possible incompatible semantics, as it has happened so many times.