While Metal might be easier to use, i'm pretty sure it is still easier to have to worry about Vulkan alone than Vulkan+Metal. And Metal predating Vulkan is real

While Metal might be easier to use, i'm pretty sure it is still easier to have to worry about Vulkan alone than Vulkan+Metal. And Metal predating Vulkan is really only of concern to code that existed before Vulkan was made available (which wasn't that much).