Honestly I don't get / understand why all the backlash. Metal is offering what most of Vulkan can do and making it even easier then OpenGL. And unless you are a OpenGL zealot, any sane game developers would have told you Direct X 9 already exceed OpenGL in most way. As a matter of fact I will go about saying compare to Direct 3D 9. OpenGL is higher level that should be compared to Direct3D 10, not 11. You need to write a hell a lot more code to do something what you previously thought were simple.

You are trying to squeeze out every last 10% of performance in exchange for lots more development time. Vulkan, you need to know exactly what you are doing. But you will have to ask a professional game developer for better judgement. I would not argue that Apple is not the best development environment for the Apple platform, or Windows for the Windows platform. Where, and this is important, support for cross platform tools determines hostility or support. With the recent github purchase it gives the oddly dissonant experience of having Microsoft being the 'developer friendly' OS company and the MacOS being the 'developer hostile' OS company.

I don't see a Metal port coming to Linux in any reasonable way any time soon, and I don't see researchers giving up OpenCL or even OpenGL any time soon, so it just means that Apple is going to forego that business. The key being that if you've got a technology that works on both server farms for production and workstations for development, you support that so that your OS is a viable candidate for the developer workstation. The movie houses that were rendering movies were using OpenGL on their renderfarms and its lack of availability on Windows kept windows off those desktops. It kept a lot of commercial software off the Windows platform and left it on Workstations like SGI and DEC had.

Mac os opengl support