Worse, RDNA3 and RDNA4 aren't fully supported, and probably won't be, as they only focus on chips that make them more money. If we didn't have Vulkan, every nerd in the world would demand either a Mac or an Intel with Nvidia chip. AMD keeps leaving money on the table.
If you are on an unsupported AMD GPU, why would you ever consider switching to a newer AMD GPU, considering you know that it will reach the same sorry state as your current GPU?
Especially when as you say, the latest generation is slow to gain support, while they are simultaneously dropping old generations, leaving you with a 1-2 year window of support.
Eh, YMMV. I was using rocm for minor AI things as far back as 2023 on an "unsupported" 6750XT [0]. Even trained some LoRAs. Mostly the issues were how many libs were cuda only.