I've used Unix in the 1980s the first time and learned that whatever your preferred editor is, you need to know vi, because vi is always installed. That has been true in my experience with a single exception. In a recent embedded Linux I used they had only nano available.
So what is the story behind JOE and what is good about it?
Back in the day (in the 90s) I was just starting out with linux, and had to install slackware from floppies I carried to school and to the library, a handful of packages at a time. I didn't have documentation packages installed yet, but I did have some howtos. So I had to edit some files, and I tried the "standard" editors - vi and emacs. I didn't know how to quit vi or emacs. I'd end up trapped in them, and eventually figured out I could Ctrl-Z and kill the process for vi. This didn't work on emacs so I'd end up switching to a second virtual terminal and then kill the emacs process. I had no idea what I was doing, and being unable to get out of a program and get back into a safe known state was quite traumatic to teenage me just getting into unixy stuff. JOE was there for me. It did what I needed it to do, it told me how to operate it, and I never once got stuck in it. Out of gratitude, I used it exclusively for years. It's zero bullshit, it edits files, it doesn't let you down.
There are a few greybeards and I mean that literally who swear on WordStar, GRRM most famous of them but Robert J. Sawyer does too. So it's not unreasonable to think there are other, less famous people who still use it? and want to use an editor with the familiar keybindings.
Not me. I am completely up to date with software and my favorite word processor is WordPerfect 5.1.
For long running edit sessions I use real emacs; I know you can set that up in a client-server arrangement to avoid the startup speed problem, but I never had the effort to investigate that; besides, sometimes you want to edit a file as root, who won't have a long-running emacs.