If it's truly "any" kind of Numpy array typing won't help much there I agree.

But often it can be helpful to know the shape of the input and the shape of the output. Eg are we working with a 2D,3D or ND array.

Before 3.11 it was not simple (possible?) To type this. But https://peps.python.org/pep-0646/ makes it possible. If somewhat clunky on the definition side.