Apple is all about accelerating tasks they care about in custom silicon. They can run video editing as fast as a GPU with much less power draw.
The GPU is needed for 3D rendering and generic parallel computing of things they don’t have custom silicon.
I can see them integrating some FGPA functionality into the mix down the line for stuff they don’t want to use custom silicon.
Still hoping they are not as far so they still adding support for RDNA2.