CS PhD and professional software engineer here. I can edit files very slowly and inefficiently in both vim and emacs but it would be a mess to use them for real work.
Some people never learned either of the editors. So what? The physical act of writing text was never the hard part of software engineering.
Someone who cannot competently use either vim or emacs is not a developer.
> The number of non-devs that can do it is far lower.
The emacs paper talked about departmental secretaries using — and extending — emacs. Human beings are far cleverer than we like to think.