Your app should work in a read-only mode without JavaScript.
Per usual, Jeremy distills things down to simple and unobjectionable points. So many of the arguments against progressive enhancement seem to follow the the thinking from when we collectively believed that sites should look the exact same in every browser.
Progressive enhancement isn’t either/or. It’s a helpful spectrum where the more functionality that can be accessible without JavaScript the better, but just because it may not be pragmatic to have everything accessible without JavaScript all the time, there’s plenty of ways to ensure information can still be accessible without massive engineering efforts.