You could tie CSS/JS event handlers to HTML elements, but if someone edited the HTML file and changed the hierarchy, things broke. You could tie CSS/JS event h

You could tie CSS/JS event handlers to HTML elements, but if someone edited the HTML file and changed the hierarchy, things broke. You could tie CSS/JS event handlers to class and id attributes in the HTML file, but you'd have to add those attributes into the HTML file to target the right elements. Web SoC always felt more SoF (Separation of Files) to me. There is no advantage in putting the HTML/CSS/JS into separate files if making routine changes requires visiting multiple files. React puts it all in one file, which makes me think that the concern is the Component and not the individual browser parsing libraries.