Yeah, it makes no sense. The standard is OpenGL, Vulkan, but Apple ditches it just to be different or something. At least some big game engines support it, e.g. OGRE, so if you do want cross-platform dev, it's possible.

Even the cross-platform stuff tends to not support Mac as well. Like CSGO had a Mac version like the other Source-engine games, but it never worked quite right on Mac. I had input lag and inconsistent framerates, and it's not that I cared about winning, but the game was painful to play like that. Game was perfect on the same machine running Windows via Boot Camp.

Also, there's Vulkan on Metal, but there's translation overhead, and I have no idea what other issues it causes. Dolphin emulator did some research on that.