Well, yeah that was expressly known about CoffeeScript. It pushed JS to the future and was expected to be not useful whenever JS gained more features, but that would take a long time. And some of the syntax features weren't adopted, which meant CoffeeScript seems like a different thing from JS but it wasn't intended to be a departure or permanent.

But JS moved faster and babel was made and eventually we could use JS-future even when browsers hadn't updated yet and CoffeeScript wasn't needed. But it was pretty easy to translate it to JS, commit that and keep rolling. CS was great at the time.