I got the sense that the article was advocating for using good semantic machine readable content over HTTP instead of (or at least in addition to) JS-only div s

I got the sense that the article was advocating for using good semantic machine readable content over HTTP instead of (or at least in addition to) JS-only div soup so that automated agents like the new wave of LLMs can easily pull out the important details without spinning up a headless browser and rendering the page first. I have the same interest but for the purpose of crawling and upstart search engines. If indexing every page required running the page in a headless browser first, the barrier to entry for new search engines is a lot higher.