Yea, honestly you probably just don't understand. FE frameworks solve a specific problem and they don't make sense unless you understand that problem. That TSoding video is a prime example of that - it chooses a trivial instance of that problem and then acts like the whole problem space is trivial.

To be fair, React is especially wasteful way to solve that problem. If you want to look at the state od the art, something like Solid makes a lot more sense.

It's much easier to appreciate that problem if you actually try to build complex interactive UI with vanilla JS (or something like jQuery). Once you have complex state dependency graph and DOM state to preserve between rerenders, it becomes pretty clear.