This could be the start of a breath-first approach, where you start with very little code, and then dig deep into things like autograd or "backprop" as you get interested in such details.
It seems to me that trying to give explicit formulas for gradients is just swamping the beginner with unnecessary details that don't help to build intuition. I think the author made exactly the right choices.
It used to be that some NN tutorials would swamp the beginner with backprop formulas, which beginners were forced by their professors to memorise. I don't think this succeeded at doing much; it only made the subject seem more complicated than it needed to be; and I think it should all be abstracted away into autograd.
It seems to me that trying to give explicit formulas for gradients is just swamping the beginner with unnecessary details that don't help to build intuition. I think the author made exactly the right choices.
It used to be that some NN tutorials would swamp the beginner with backprop formulas, which beginners were forced by their professors to memorise. I don't think this succeeded at doing much; it only made the subject seem more complicated than it needed to be; and I think it should all be abstracted away into autograd.