I think he/she advocates for websites to be generated on the server (if they're dynamic) and not passing on that burden to the browser. Specially if the browser language was created to add drop-down menus and cool snow effects, not to generate a complete html website.
That's why I'm confused, that's exactly what this article is about. You're using React SSR to do the same thing you would do using RoR or JSP... unless the gripe is specifically with JavaScript as a programming language.
