I'm not a web developer, but I dabble in it because I find it interesting. I went through some courses like The Odin Project and others to learn the basics of HTML/CSS/JS, and I thought it made a lot of sense: HTML structures the page, CSS handles the style, and JS handles the functionality.
However, after working for software companies for a few years, it seems like almost nobody uses these technologies in the way they're presented on websites like w3schools to make web applications. Instead, they use component-based frameworks like React. To me, these frameworks seem way more complicated than HTML/CSS/JS, and I don't understand what problem they're trying to solve. What makes the trade-off of all that extra complexity and abstraction worth it? Aren't HTML/CSS/JS perfectly fine and time-tested tools for web development on their own?