I think "multiple dispatch" is the wrong word. "Dynamic dispatch" is a much better word for what Python does. It's a ridiculously powerful feature. It lets you wrap and replace functions at runtime, which gives you incredible monkey-patching power, which is important to people programming in the real world.

My favorite example: Suppose you have a naive O(2^n) recursive factorial() function. I can write "factorial = memoize(factorial)" and suddenly your recursive calls are to my new wrapped function, which references your original implementation inside its closure. This is only possible because your recursive implementation dynamically dispatches by name. I have turned your O(2^n) implementation into an O(n) implementation.

In an unsafe systems language like C, I would only be able to accomplish the same thing with some severe memory hacks, and in a language like Java or C# I don't know how I would be able to do the same thing without some serious involvement in runtime reflection tools, and maybe even some decompilation.