Matrix multiplication is the bread-and-butter of ML (both training and inference), for fairly obvious and solid reasons. Luckily for us, it's also very important in all sorts of domains, including graphics, rendering and gaming. That's all there is to it. There's no real "subsidy from the gaming industry", only a cross-subsidy situation in which common problems that are shared across domains can take advantage of the increased scale that comes from sharing the GPU-compute platform.

I'm not sure what you mean by "ML features", but AMD/ATI's dismissive attitude towards the ML and GPU-compute communities is looking quite silly by now.