HTML was never the problem. It is simple enough to be taught to non technical people. The issue is styling it, making it looks beautiful. And this is where the truth appears: HTML was not designed for building magazin-like pages but hypertext paper books. The very recent introduction of CSS grid shows it.

If HTML could be used as a collection of widget akin to Windows Forms, with an easy grid system (somewhat like XAML), there building an UI page creator would be easy, and user could edit the output unlike with the current tech.