I think for a system that can basically do EVERYTHING, HTML is quite well designed. And I think keeping backwards compatibility for SO long is a big achievement

I think for a system that can basically do EVERYTHING, HTML is quite well designed. And I think keeping backwards compatibility for SO long is a big achievement and a good thing. I also think that if we could roll back time and had the knowledge of today, instead of fixed elements with user-agent styling and hard-coded restrictions, I would've crafted a system of arbitrary nodes that can have modifiers stacked on them. So instead of <ul> you could use <Features list>. This would minimize the very different but basically same CSS properties as well and trim out A LOT of HTML tags. Think <Comment collapsible link> instead of wrapping a <details> in an <a>. That's basically how React and Vue started out with the component system, but I'm thinking more of a GameObject & Component system like with Unity.