This is precisely the core difference I was talking about. If you want someone to learn about the details of their differential equation solving, then you coul

This is precisely the core difference I was talking about. If you want someone to learn about the details of their differential equation solving, then you could probably construct an argument for Sage. But that is not always the educational goal. Indeed, for everyone but college level STEM people in a "Diffeq solution methods" class, it will most likely not be the goal. Mathematica says: You shouldn't have to know the minutiae about differential equations in order to solve them; we'll figure out the details for you! SageMath says: We'll give you a buffet of solvers with different internals so you can pick the one that's right for your problem! Both approaches have merit, and drawbacks. But if you asked me which approach I support, I'd have to go with Mathematica. Theirs is more ambitious, and far more powerful if they are able to "get it right."