I think the part that is hard to grasp is that React essentially has it's own runtime tangled with JS. With the introduction of hooks, there are non JS things going on, which is why React relies on the quirk of having the same order and number of hooks in your component. It also has Suspense which allows you to exit from the render function and return to that spot, which is definitely not a feature of JS. So yea, it's weird. I think the interesting question is trying to figure out what this means for the next version of React. I would like to see if it takes a page or two out of Svelte's book.
There are no "non-js things" going on. I'll grant that they're doing some out of the ordinary things in order to support hooks and suspense, but it's still just JavaScript.
Edit: If you want to see how hooks are implemented without needing to understand the React codebase, Kyle Simpson has a project that provides hooks for non-React functions, the implementation is all in one file: https://github.com/getify/TNG-Hooks/blob/master/src/tng-hook...
