It's the right platform, but it's the wrong authoring experience for people who might not be able to code at all, much less understand the nuances of CSS and how it interacts with the DOM. People using LaTeX don't want to code something, they want to write something and just have requirements that go beyond the typical use-case for "writing something". A layer is needed on top.

Maybe that could take the form of a single JS and/or CSS file that gets dropped into an HTML page and then the author can create their documents with nothing but special tag attributes/classes. But likely it would need to be even more abstracted than that.

Here's a good attempt that's being made. It's an extended version of Markdown that covers charts, equations, etc.: https://casual-effects.com/markdeep/