And Rocm supports the higher RDNA2 and the highest-end RDNA3 consumer GPUS - [0], though only the top RNDA3 cards in linux [1] (officially - other cards often do "work" but YMMV)
One thing Nvidia are much better at is supporting the whole stack - while I doubt many people are actually running much ML on 8gb mid-low end cards, it seems a hook for sales if people "could" do that, and a starting point for personal experimentation. I know multiple people who buy low end Nvidia GPUs because they "might" experiment with CUDA some time in the future.
[0] https://rocm.docs.amd.com/en/latest/release/windows_support.... [1] https://rocm.docs.amd.com/en/latest/release/gpu_os_support.h...