That just leads to every page on the web hosting its own copy of jQuery. The whole purpose of external JS is to reduce load times by sharing cacheable libraries (admittedly with the side benefit of less bandwidth for the host).
And if you think a whitelist would work, all it takes is one look at how rapidly new JS libraries come and go to render that unfeasible
And if you think a whitelist would work, all it takes is one look at how rapidly new JS libraries come and go to render that unfeasible