Am I misunderstanding, Bjarne’s 2nd edition Chapter 3 of A Tour of C++ section on namespaces as it seems to imply that once a using-directive is used, we can’t qualify it?

By using a using-directive, we lose the ability to selectively use
names from that namespace, so this facility should be used carefully,
usually for a library that’s pervasive in an application (e.g., std)
or during a transition for an application that didn’t use namespaces.

If this isn’t it, what does this citation mean? I didn’t see it posted in the 2nd errata. I tested this out with this code and it compiled and ran without any issue.

#include <iostream>
using namespace std;

int main()
{
    std::cout << "worksn";
}