Although this isn't directly related to the article, I can't upvote this enough. To be clear, the article is almost solely about contrast between text and back

Although this isn't directly related to the article, I can't upvote this enough. To be clear, the article is almost solely about contrast between text and background colors, not JS heavy frontends. But I think what you've stated is very true and is also my opinion about the current state of web frontend. Like another user said here, the contrast is a result of designers working with a page with too much content, and trying to reduce the feeling of content overwhelm. I don't think heavy JS frontend is directly related to that. But what you've said should not be discounted.