I'd really enjoy a detailed writeup on why the graphics industry has been so fragmented. I'm not a graphics programmer myself, but from the outside looking in, OpenGL looks like it has fallen victim to design-by-committee. If I had to guess, the "big" players want to propose changes to the API which are closely reflect ideal usage of their own hardware. This typically upsets another big player, so the compromise is that both changes get added to OpenGL and the users are caught in the crossfire.

I think in an ideal world, Vulkan would have arrived years earlier and became the central standard that succeeded where OpenGL failed. However, Vulkan is the phoenix which arose from the ashes of AMD's Mantle API in the mid 2010s. Thus, Apple chose to do what Apple does best: eschew common standards for their own proprietary solution which only works for their platform. It seems they've made this gamble with graphics and their structuring their machine learning ecosystem to be quite similar.

From a computer architect's point of view, seeing all of this diversity reminds me of the days of the console wars. Architects were willing to make crazy (at the time) design choices with their system architecture and developers were expected to learn how to leverage it to the best of their ability.

Hopefully someone with more experience than I can comment on whether these educated guesses amount to anything.