AMD have repeatedly dropped the ball when it comes to software support for compute and AI. Their hardware is quite capable, but very few people can actually make it work, which means most of the existing models have poor AMD support.

This is getting better with ROCm and such, but that's Linux-only and only works for a subset of tasks.

Both Intel and Apple have better "out of the box" support for ML and the ability to invest more into making these things work (e.g. Apple have implemented Stable Diffusion against Core ML themselves)