Thats true in small functions, but that's also true for statically-typed languages with type inference. In OCaml, the same function would also be

    let add x y = x + y

Looks reasonable to me, and this is statically type-checked

If I were making an argument in this case, I'd say that several other languages have fulfilled the "readability" benefit while also fulfilling orders of magnitude higher performance and type safety garuantees. This implicates that one case is write only instant legacy code and the other will be highly maintainable going forward if the codebase and team need to scale in size.