It feels like people use these editors for the novelty of it and not because it's truly the best for productivity.
The thing I love most about emacs is that it is joyously consistent. The same key combination to jump ahead by a word works everywhere, such as when you're opening files or navigating directories. This consistency means that I am often very efficient trying new packages that I have never used.
Maybe you've never seen someone use emacs in anger? If so, check out this video of Steve Yegge doing some stuff in Emacs: https://youtu.be/lkIicfzPBys?t=142