I've seen people, lead and principal engineers, who refuse to learn modern JS, insisting that since it was bad in 2006 its bad today.

It's still bad, though. That's not the reason why, but it still is. All the frameworks and things like TypeScript try to work around and hide the uglyness and stupidity of JavaScript, but they neither remove nor fix it. The way HTML was initially designed is the exact opposite of how it is used. It was intended to present data in a standardized way and leave the rendering and styling to the client application. People tried to create pixel-perfect designs with it. The entire resulting technology stack was created by idiots for idiots. And JavaScript is consistent in the misguidedness of the endeavor. All the marketing talk about platform independence is bullshit. It is easier to write platform independent GUI applications in C than in HTML + CSS + JavaScript. All the frameworks and languages transpiling to JavaScript trying to belie that just lead to a breeding ground of incompetent GUI developers doing esotheric coding ("doing it the way it is done" while understanding zilch about the fundament). The resulting developers are useless outside of their steaming pile of web GUI shit. The least worse of them are the ones promoting and perpetuating this failed technology stack by adding further layers of abstraction to try and hide that it is build on and from shit, creating even more esoteric developers in the process - by idiots, for idiots. Web GUI developers are paid less than any other branch of developers and it is completely justified.