It depends on the type of site/app you are building. If you are building a basic website (not a web application), or a simple application, you don't need React (or a similar framework like Vue or Angular). You might not even need Javascript at all.

However, as you build more complex and interactive applications, you need "framework", like React. It's essential to simply handle the complexity of such applications. You will not find a major web app that is built with out a framework (or if it is, the owners will essentially have to create their own framework).

When you're using such tools, they are how you enforce consistent UI. Take Tailwind, the hugely popular CSS framework (I believe its #1). They have nothing to do with Javascript ... but even they willl tell you (https://v3.tailwindcss.com/docs/reusing-styles#extracting-co...):

"If you need to reuse some styles across multiple files, the best strategy is to create a component if you’re using a front-end framework like React, Svelte, or Vue ..."

The author is completely mistaken in thinking React ... or even that layer of web technology at all (the development layer) ... has anything to do with what he is complaining about. It has everything to do with design choices, which are almost completely separate from which framework a site picks.