Both Unity and Unreal support metal well (and for a long time, better than Vulkan), especially due to iOS. Even many proprietary engines do.

Even before Vulkan and Metal existed, OpenGL was consistent (before Apple stopped supporting it) and there weren’t many more native games then either.

Someone will no doubt bring up reusing Proton, but they’ll gloss over the differences in platform and also that Game Porting Toolkit exists and does the same thing.

The reality is that, until recently, the number of Mac systems that were gaming ready was a very small number that wasn’t worth focusing on.