Javascript is an easy language only for trivial use cases. Once you start having to deal with real-time async state across multiple components, it becomes very much not so easy.
These frameworks aren't meant to do what basic DHTML did back in the day. Those use cases are still served just fine by basic scripting or serverside interactivity.
What these frameworks allow are entirely new classes of featureful client-side applications (think Google Workspace, Maps, Earth, dashboards, games, sketching programs, photo editors, etc.) that would be HELL to write in vanilla JS.
If you're not building something like that, nobody is forcing you to use those frameworks. But at a certain level of complexity, those frameworks are worth their tradeoffs. Beyond that, at an even higher level of complexity, they become necessary... or you end up writing your own framework.
The reason these see such adoption isn't because devs are getting easier, but web apps are getting orders of magnitude more complex than back in the day.
I don't think the bar to entry to has necessarily gotten much higher; rather, the skill ceiling has increased a thousandfold... you can still be a basic JS dev to add a basic form validation and submission or whatever, and you don't need React for that. These days vanilla is plenty powerful for simpler use cases. But you can't easily scale that up to the level of modern web app interactivity. Or if you can, well, build it and show people and see if you succeed in convincing them "this is better than Vue/Svelte/React/Angular". People are always saying that, but I've yet to see a complex web app NOT written in some sort of abstracted framework. If you manage to do it, it would be very impressive and way more convincing than just saying "frameworks are unnecessary" -- because as far I can tell, along with thousands of others of web devs, they are not.