I learned it through Spacemacs and it's one of the things that really made modal editing work for me, so I was thrilled to discover that Vim itself also supports it. (I'd tried to learn Vim before, but always having to jump over to the Escape key was a huge downer for me, and coming from Emacs I'd already mapped my CapsLock to Ctrl--though the idea of having it be Esc if pressed by itself is intriguing and I need to look into it more!)
