A sprinkling of type annotations to help with ambiguity is nice. However, I don't recall the last time I spent ages figuring out what type I need to pass to a function if it simply wants a builtin type. It's usually the semantics or a library-unique type (ugh!) that I have to look up.
It's better than writing it in a docstring, because a type checker will tell you to change the type if you change how you use a variable.
Does everyone need to go all the way and type 100% of things and use heavily generic code to represent all possible cases? Well, that would be wonderful, but just sprinkling built-in types is already a massive improvement over no types at all.