To that point, QuickDraw is still shipping in MacOS although it's officially deprecated. Pretty impressive for an API that began life in 1979. I will dock it for never supporting more than a 1-bit transparency mask, but Atkinson had left Apple before that became important. I think he quit around the time Jobs was first fired.

He made HyperCard on his own and licensed it to Apple for cash, though he stipulated that they had to release it for free. Unfortunately, HyperCard's biggest legacy is only Myst, and the Tim Berners Lee shout-out.