Apple is using Metal because it's a modest improvement over OpenGL (in some areas; it's a regression in others) and, more importantly, their OpenGL implementation is extremely buggy.
You haven't said anything about Vulkan vs. Metal, and you can't, because Vulkan is a better API for the reasons I described upthread.
Full disclosure: I have colleagues and friends on the Khronos standards group, and I don't like seeing their work bashed without specific technical reasons.
You haven't said anything about Vulkan vs. Metal, and you can't, because Vulkan is a better API for the reasons I described upthread.