[foobiekr]

It does, though.

Many times bottlenecks and missteps are not really visible until you can see how your decisions and assumptions encounter reality especially when every other chokepoiht has been removed.

Unless they did their development on Windows or on hardware that has never shipped, Apple isn't really in the position to have evaluated how well Metal works in reality.

I would add that the awkwardness of some "good" API designs is often not revealed until much later (and this is doubly true in the graphics space where there is ample evidence of API choices revealing themselves to be stuck with what turned out to be bad choices some times later).