I'd say Spring and React are less powerful than just plain Java/Javascript, in fact having any framework usually reduces the "power". I believe "power" in this

I'd say Spring and React are less powerful than just plain Java/Javascript, in fact having any framework usually reduces the "power". I believe "power" in this context describes the amount of freedom the language allows. The less powerful the system is, the better you can reason about it and the more external tooling you can add around it without breaking corner cases. A webpage is less powerful than a .exe running on your system, but that is what makes it so useful - you can run it at 144 fps, use it with a screenreader, custom CSS, high DPI (even if the webpage was written in the 90s), etc. and all of this relies on the lack of power of the webpage.