It’s about the network, not the website.

the markup might be clean but it's pretty ugly and network inefficient because it's full of boilerplate that is only required because html also supports 1000 times more nonsense than this site uses, so you have to type <p></p> to render every line of that text, or <a href=""></a> to just render a link. you need to do <h></h> for headings. if all you want to do in your content is those things, that markup is ridiculous.