They don't care because they can't make money off it. They know very well that Steam would outsell their App Store offering so greatly (with good reasons) if they supported Vulkan that they don't see the point.
They push their Metal API not just for the hardware matchup but because it allows them to trap developers into optimizing for their technology only and getting them to sell their games in the App Store.
Because the minute devs start looking into options for cross-platform dev/deploy their Metal/App Store combo is just not very enticing compared to the alternative.
But they would rather lie about caring for this use case and they would need to have better GPUs in the first place, but at least it looks like this should be improved with M4.
For all the big talk they give, their GPU in the entry level Apple Silicon chip doesn't even match the power of a current gen console (either PS5 or Xbox series X have better GFLOPS).
The Max versions are better but they only come in devices starting at over 2.5k€ starting price (still with lots of compromises most likely) and those get absolutely trounced by hardware at this price point that features dedicated GPUs, obviously.
But they will very much remind you about how great battery life is, because it is all that matters, right? right? (Desktops, hello?)
Unless you can justify one of the Max variants for other things, there is not much point bothering with it. If you really want a Mac, it will still be better, faster and cheaper to just buy the most basic Mac you can get away with and get a console or a custom PC with the rest of the money.
It is very sad, but this is the state of things. Gaming on Apple was never very good, but at least before Apple Silicon there were some variants of iMacs/MBPs that were decent enough and not breaking the bank too much (with Windows support for even better performance).