You could say the Same about non IOMMU CPU virtualization. The problem here is AMD and Nvidias disgusting greed that has held back security by at least a decade. GPU virtualization (vGPU/MxGPU) is supported but only if you pay ridiculous enterprise licensing. This should be a first class feature like VT-d and would enable a usable Qubes desktop and Microsoft's VBS.
https://en.wikipedia.org/wiki/GPU_virtualization#Mediated_pa...
MS also killed RemoteFX because of security.