> And it is becoming increasingly clear to me that there’s a whole swathe of Frontend Engineers who don’t know or understand the frontend-est of frontend technologies.
I would need some data on this, since it sounds like this claim is backed by anecdotes. None of my co-workers struggle with this and there's lot of frontenders in our company. Semantic HTML's usage is now baked into VS Code in a tooltip.
Yes, every web developer should be at least moderately good with HTML. Can we agree on that? Good :) Learn a bit CSS and now you have superpowers.
HTML only provides the LEGO blocks for the web, but the web is much more than that. It's an interconnected network of information with rich media. What matters is the information persistence, quality and accessibility.