Very correct take on the JS landscape - thanks.
I began with vanilla JS before there were any "popular" libraries or frameworks, i.e., 1999. As a result, I became a JS guru in order to accomplish the neat-o-nifty stuff that people think of as standard today. With experience in both Functional Programming and OOP languages, I could optimize "the weight' of my JS solutions. When I later worked in shops that had already adopted libraries, I was usually the only one who could debug the craptastic code produced by developers who relied on JS libraries without a solid foundation in vanilla JS.
Too many companies have "drunk the Kool-Aid" about reduced development time and shared understanding as motives to employ libraries (or frameworks). This foolishness is not restricted to JS - it is entirely general to all language environments. I see sloppy programming practices, ignorance of DOM and JS (and just plain, old programming) principles, and laziness as the primary "benefits" of using JS libraries. Too often, these "benefits" come at an additional cost of bloated bandwidth, e.g., using 1% of jQuery's functionality to avoid writing a 10-line function in vanilla JS. If your shop uses a library to solve problems the developers can't solve with vanilla JS, you likely retard your programmers' professional competence and are constantly at risk for catastrophe.
The developers' time is entirely the most expensive part of the IT pie. Reducing those costs is a perfectly laudable goal. Libraries MAY reduce that expense during development (if ever). Long term, during evolution and maintenance phases, where the main expense happens in an app's lifecycle, not so much. However, project managers want FAST development and usually have no direct responsibility for later support costs.
That said, try getting a job with ONLY vanilla JS. Without a raft of library (and frameworks) to list as elements of your toolkit, your chances of finding work are slim. Managers, human resource agents, and recruiters are usually gullible ignoramuses when it comes to hype about "new-&-improved" software tools.
Again - thanks for the very accurate article.