jQuery rise (but also underscore and others "low level libs) was interwined with the need of common functionalities, such as the DOM manipolation and the ajax calls. I still remember when all you could use was the .innerHTML property and the "new" DOM level 1 api [ https://www.w3.org/TR/1998/REC-DOM-Level-1-19981001/ ]. jQuery selectors were so game-changing that the "new" DOM api were basically copied.
I understand how incredibly difficult is to find a good balance between an "anemic" stdlib (like the barely sufficient c stdlib) to the giant ones (like java has had), moreso that a bad/poorly secured function should still be mantained "forever" for backward compatibility.
Still I think that this movement should go forward to finally have some form of "batteries included"