Pointers to std::string are almost never required, though. A pointer to std::string is not something you have to use to write a string handling C++ program or module; and such a pointer p is itself not a string, *p is (if p is non-null and valid).

About the only time you would need a pointer to std::string when calling some C API that takes a callback function with a void * context, and you'd like that context to be a std::string. Then you might take the address of string object to pass to that API. (That pointer would likely never be null, but could go bad due to lifetime mismanagement.)

Most other uses of such a thing would be unidiomatic. Whereas, in some languages, string references that can be null are foisted on programmers as the standard, idiomatic string representation. That's a big difference.