I'm not saying the ideal frontend dev writes no JS. I'm saying they write as little as possible. Some times you need JS, nothing wrong with that. The vast majority of the time you don't. And if you do I'd say it's a self-imposed requirement (or a direct/indirect result of a self imposed requirement) most of the time.
Recently I took a little dive into making some pages, that have fallback for when the user doesn't run JS. Those pages are polling an API and displaying updated status. I made sure the pages can be reloaded and show updated status information, and telling the user, that they can simply refresh the page to get that updated information, but only showing that hint about reloading, when they do not run JS. Thus I built a workflow, that people can use whether or not they run JS. I did that, because I think it is the right thing, and because I often preach, that most sites should work without JS.
For me as a mostly backend dev, this was actually quite easy to achieve. Tiny modification of the backend API, some work in the frontend using JS to remove hints that should not show when JS is running, and voila, it works. Of course my pages are very simple in nature, but the same principles can be applied to larger pages. One could even link/direct to different pages, depending on the user running JS or not, and then have a workflow without JS and one with JS. It is all possible and only a matter of wanting to make an effort. Of course, modern JS frameworks do not really encourage this kind of design. Though server side rendering becomes more popular these days, I don't think we are quite there yet.
A page that is blank when not running JS has exactly zero accessibility.
I'm not saying the ideal frontend dev writes no JS. I'm saying they write as little as possible. Some times you need JS, nothing wrong with that. The vast majority of the time you don't. And if you do I'd say it's a self-imposed requirement (or a direct/indirect result of a self imposed requirement) most of the time.