I'm a fan of simple HTML, too-but I don't believe it has any real impact on accessibility over JS with accessibility in mind. If there are specific cases where that is not true, I'd love to know them
- a simpler page is typically more usable as well, and
- sometimes you have inherent complexity that it’s also possible to make accessible
It’s much more that JS tends to make your page being modified in unexpected ways. If all you have is a voice reading the page, you may be submerged by information each time the dom changes and you may have a hard time understanding what is the context of the element which changed.
Pointing out to actual accessibility issues would have been a much better argument than generic complaining about the website requiring JS.