Have you considered that multiple dispatch is obscure because it requires jumping through such hoops to implement in most mainstream languages, rather than because of its lack of utility?

The short answer is that the existence of multiple dispatch isn't motivated by the visitor pattern.

Moreover, multiple dispatch isn't obscure at all.

C++ has it, but only statically, for instance, in the form of overloaded functions. C++ chooses a function overload by looking at the types of all parameters and arguments.

Multiple dispatch is similar, but the run-time types of the arguments are used.

This is broadly applicable in making all sorts of situations nicer.

Why have functions and control structures when we can just jmp?