The problem space Vulkan and Metal solves is not high level cross platform graphics (which OpenGL tries to solve), it’s low level control over the GPU. That’s

The problem space Vulkan and Metal solves is not high level cross platform graphics (which OpenGL tries to solve), it’s low level control over the GPU. That’s the problem they’re trying to solve, it’s not about cross platform. You might ask, ‘Then why is OpenGL deprecated?’. The answer is that Apple is just deprecating it’s own support since there’s a more low level API, OpenGL should be implemented on top of Metal, which (for example) MoltenGL is.