Because finite difference approximation is not automatic differentiation, and I think it is a good idea to have some functionality in the core package for people that don't want/can specify gradients for their loss function but also dont want to get into automatic differentiation (i.e. want to use the old-school approach)
Because finite difference approximation is not automatic differentiation, and I think it is a good idea to have some functionality in the core package for people that don't want/can specify gradients for their loss function but also dont want to get into automatic differentiation (i.e. want to use the old-school approach)