I'm talking about my code specifically. With React I can pull in a massively complex UI component in few lines.

The complexity is shifted to the library that hopefully has thousands of users so is mostly bug free. It simplifies my code at the expense of moving complexity to the shared project. Much preffered since my code will see orders of magnitude less usage than the library itself

I care debugibilty and maintainibility. Many projects on github have very short life cycle. If it go unmaintained, how easy can I take over it?

I would argue that most websites have a lifetime similar to the components :). For the ones that don't, backwards compatibility on the web is amazing, only thing to worry about is security vulns

You're correct that simpler code is better, but here's my argument: Large jQuery applications are not simpler, have more bugs, are harder to maintain and have poorer performance than React applications.

jQuery is a DOM manipulation utility library. React is a view rendering library, favoring composition and isolated components.