It’s a bit of a cheap shot to characterize something as ‘argument from tradition’ when the clear purpose of the article is to criticize recent developments. I am not concerned with the conflation of JS and CSS simply, and solely, because it is a new development. I consider it a problematic new development.
CSS and JS are different languages with different rules, idioms, and surrounding cultures. Asking someone to speak JS in order to write CSS is like asking someone to learn French in order to write in Dutch. Some people can speak both, which is great for them. But it is still a needless imposition; an arbitrary barrier to getting things done.
Stylesheets pose none of these problems. In fact, if stylesheets were invented today, I strongly suspect we’d be vaunting the technology for its independent and portable nature. But stylesheets are not new, and so there’s no interest in stylesheets from neophiles.