Since we write a lot of JavaScript now, we tend to write less HTML and css code.
We used to have Ext.js that turns your HTML into something like this:
<div class="div">
<div class="content">
<div class="body">
<div class="text">
<div class="link">
A clickable link here
</div>
</div>
</div>
</div>
</div>We now have React.js that encourages you to write HTML in your JavaScript. They even build the whole event system. People using JavaScript (EG: form validation) to make sure the HTML has consistent behaviors across different browsers.
It seems like every HTML tag just have some special use agent. For example, an an tag is an anchor link. You can click to go to another website. Text is blue with underscore. You could write JavaScript (or/and css) to turn a <div> into <a>. Or can you?
Note: This list does not include things like calling createElement() in your JavaScript, because an <a> created by createElement() is a real <a>.
Note: There are other important reasons: semantics, free functionalities, default styles and performance.
No, you can't command your VoiceOver to call a <div> an anchor link. In fact, you can hardly control your VoiceOver in general.
EG: "Open Link In New Tab". You can't add this to your "right click menu" in JavaScript. No You can't. You can't even do customize context menu in most browsers.
Yes, search engines do run JavaScript now. No they won't treat a <div> with a click event listener the same as an <a>. They will probably ignore the changes made by JavaScript in your <head> metadata.
Surprise! The only way to do a form post is through HTML.
This is the only way to have a "browser" inside your website.