As I already wrote in another thread, Metal is pretty much OpenGL with some overhead removed. I can't see anything in the specs that would hint that Metal API worries about the hardware. Its pretty generic actually.
Metal worries about the hardware in the same way that OpenGL does. OpenGL is the layer you stick inbetween your software and the hardware (or at least the hardware's lowest-level interface) to make it so you don't have to do hardware-specific things (in an ideal world; in the real world there's still some things you have to do to get the best performance.)