You're taking a specific example using React and generalizing it to the entirety of FE development. React works in such a way that it's easy to optimize individ

You're taking a specific example using React and generalizing it to the entirety of FE development. React works in such a way that it's easy to optimize individual components, but extremely difficult to optimize the entire system. Most FE frameworks, libraries, languages, and environments don't work that way. I will grant you one thing: on the backend, you can use whatever languages and operating systems you want. On the frontend, you're pretty much stuck with javascript and the browser (css, DOM, event handlers, etc).