Why do array, vector operator[] not have rvalue qualified overloads?

Strange, but why do these operator[] functions not have rvalue ref qualified versions that return rvalues to the internal data members?

C++14 changed the rule that the builtin operator[] to evaluates to an rvalue (more specifically an xvalue) when applied to rvalues, but this now does not seem to be consistent with the overloaded operator[] provided in std::vector and std::array