In a modern web framework you still have HTML and you still have CSS files.
The problem is JavaScript and in particular the way that you interact with the DOM: browsers use an imperative API, that this day is obsolete, and makes writing web applications a mess rapidly, and produce spaghetti code difficult to modify and isolate.
While practically all modern frameworks use a functional approach: you have the component, that has an internal state, a function to render DOM elements from that state, and if you need to update the view you don't directly manipulate the DOM elements, but update the component state, that causes the framework to call again the render function that updates the DOM elements as required. That is so much simpler, because you don't have to ensure that the state of the application is aligned with the state of what the user sees on the screen!
I definitely see the elegance of the modern reactive approach, but in practice I'm not sure how much better it really is. I still see spaghetti code, and I still see stupid bugs in production. Doesn't seem to matter whether it's JQuery or Vue. Right now I'd bet that careful architecture and thorough testing are still #1 for making good software.
It does often turn into a weird kind of spaghetti when it comes to things that are inherently imperative. Sometimes hooks make me feel like I’m trying to follow a Tarantino script.
The problem is JavaScript and in particular the way that you interact with the DOM: browsers use an imperative API, that this day is obsolete, and makes writing web applications a mess rapidly, and produce spaghetti code difficult to modify and isolate.
While practically all modern frameworks use a functional approach: you have the component, that has an internal state, a function to render DOM elements from that state, and if you need to update the view you don't directly manipulate the DOM elements, but update the component state, that causes the framework to call again the render function that updates the DOM elements as required. That is so much simpler, because you don't have to ensure that the state of the application is aligned with the state of what the user sees on the screen!