I remember my early days building for the web. We had no separation of concerns. We used and tags, transparent spacer.gifs, and complex table layouts to force our content into a shape. Presentation and content were a single, messy soup.
My first encounter with CSS in Netscape Navigator 4 was a mind-blowing moment. It was the first time I was confronted with the idea that you could (and should) separate the document’s structure (HTML) from its presentation (CSS).
(Also worth mentioning the author’s entire modus operandi is to promote Google’s Big Tech vision of AI-all-the-things and hence the blog is chock full of one just-so story after another. It’s quite safe to ignore completely as pure propaganda.)