Maybe it's too dry for todays culture. You can see numerous people asking for a specific way to communicate: clear single page of features, live tutorials etc
I agree that emacs comes with almost all you need to understand it, but there's one inherent flaw: it's large. It's a joke in the community that nobody is immune to a late "wait, emacs can do that ? I've been using it for N decades and I had no idea.."