The example given in the post was using <div>s rather than semantic HTML elements. The motivation for the principle of using "semantic HTML elements" comes from the lofty ideals of the Semantic Web[0]. However, these principles didn't come from best practice. Instead, someone (Tim Berners-Lee) thought that it was a cool idea and tried to convince everyone of it without demonstrating that it could actually deliver on any of the promises it made. The argument instead is that principles should be based on what is proven to work, rather than what sounds good in theory. I agree with the sentiment in the post.
[0] https://en.wikipedia.org/wiki/Semantic_Web