I think a large part of the issue is the default keybindings (the GUI is also bad, but I think it's bad in a way that's not going to be impossible to fix without screaming from people who like what's already there). It's truly only lacking a decent text editor.
This isn't to say that the keybindings never made sense; in the stage of computing before X, where Space Cadet-like keyboards were common, it was more than fine.
Currently, though? Entirely different era of computing.
Imagine you're walking in with no clue. You haven't heard of any of the memes, someone just recommended you a text editor. "It's really good! You'll be more productive!" You have no idea what in the world evil is, or why you would ever want it.
You launch the tutorial/tour/whatever it's called and immediately it yells at you to use C-v to jump to the next page. And then M-v to go backwards! If you're a normal user, your response is probably something along the lines of, "Like, why?"
Off to a good start, breaking the most universal keybinding across modern operating systems in the strangest way possible, and not only that, but also breaking one of the biggest implicit rules of keybindings.
You read a little bit more and eventually get to cursor control. Wow, somehow they managed to pick the only possible thing less intuitive than 'hjkl'! Not only that, but it's not even consistently unintuitive!
And that's not even getting into the obvious problems that come with the placement of M and C on modern keyboards.
There are a few solutions to this, obviously, but good luck trying to find a solution that isn't universally-hated.
You could make evil the default. Controversial and only slightly helps the barrier to entry.
You could make it like the Web's model of text-editing but with quality-of-life enhancements. I think this one is probably the winner. It's definitely why Sublime/VSC/Atom won, past everything else.
The Turbo C/Wordstar approach was cool, but has no mind-share today.
You could try something new, I guess? This is dangerous territory, though.
I have no idea what the solution is, but the problem(s) seem obvious. I say this all as a person who really likes Emacs. I even still have most commands memorized despite not having touched it for years now!