[chrisldgk]

While React and JSX/TSX might be somewhat of an abstraction on top of HTML and CSS, you absolutely still need intricate knowledge of HTML and CSS to build anything good with React.

In the end what you get out of your React code after your build process is vanilla HTML, CSS and JS. While you might be able to abstract some of those things away using libraries, all you‘re doing in your React code is building and manipulating HTML DOM trees within your React code and styling them using CSS (or using some abstraction like CSS-in-JS, CSS modules, etc.). To do so efficiently, you not only require knowledge of how exactly HTML and CSS work but also what React tends to do under the hood to render out your application. Even more so when things like a11y are required. A good dev also knows when to use JS to reimplement certain interactions (hover states, form submits, etc.) and when to use the native functionality instead (for example CSS pseudo selectors or HTML form elements).

All this is to say that I disagree with the notion that React devs don’t know or understand the underlying technologies. It might be different and more abstracted, but it’s still the same technologies that require the same or more understanding to be used efficiently.