What happens when it's an operation that doesn't have magic fallback methods like the arithmetic operators do? Say the code is `max(400, n)` instead. Now what? The `max` function doesn't know about your special type, so the code fails. Magic methods simply don't scale: they solve this problem in a few very specific cases and nowhere else. With multiple dispatch, you have a completely general solution to this entire class of problems: you just define a new method of `max` that knows how to handle your new number type and everything works.