By this point people don't appear to have any real clue how to write HTML anymore. Writing semantic HTML isn't significantly harder than say writing Markdown. You copy some HTMl skeleton and you literally just stack your elements into the body. I managed to do that as a 13 year old on MySpace without any deep instruction. Sure you have to close elements as well so the syntax is slightly harder than markdown, but that allows you to differenciate between for example <article>, <section> and <aside>.
I am convinced the one single thing that made HTML unusable over the time was that people wanted or needed a way to re-use parts of the page across multiple pages, like headers, navigational elements and footers.
This meant people used frames, PHP, templating engines or any other new technology mainly for the purpose of creating shared elements, simply because HTML failed (and to this day: fails) to offer a way to include one HTML file in another without having it suck (like frames definitely did, since the browser treated each subpart of the page like its own entity including caching).
I am convinced the one single thing that made HTML unusable over the time was that people wanted or needed a way to re-use parts of the page across multiple pages, like headers, navigational elements and footers.
This meant people used frames, PHP, templating engines or any other new technology mainly for the purpose of creating shared elements, simply because HTML failed (and to this day: fails) to offer a way to include one HTML file in another without having it suck (like frames definitely did, since the browser treated each subpart of the page like its own entity including caching).