If people knew what they were doing jQuery, Angular and React would not have existed in the first place. With devs moving companies every two years or so, being able to hit the ground running was very important and you couldn't afford to spend weeks or months learning the idiosyncrasies of your new codebase especially when it came to state management. That's the main problem frameworks and libraries were solving.

> you couldn't afford to spend weeks or months learning the idiosyncrasies of your new codebase especially when it came to state management. That's the main problem frameworks and libraries were solving.

Not really. Frameworks are usually created to avoid boilerplate and provide some nice scaffolding to support you while you’re coding the business layer. And a lot of them do smooth over accidental complexity, even though the architecture is generic and may hinder you in the future.

But the learning curve still exist, as most of what you interact with is custome codes, modules and components.

That's not quite right. jQuery was exactly the right tool for those of us who knew what we were doing. Browser inconsistencies in the early days were practically insurmountable without jQuery to provide a consistent API surface.