Unless the central thrust of the course is supposed to be the mechanics of a particular dated editor, the restriction described seems to be a distraction from rather than an aid to what the students are supposed to be learning.
It doesn't make any more sense than a social science course where the deliverables for most assignments are essays mandating WordPerfect for DOS. Sure, you'll learn something you might not otherwise, but it's a distraction from what you came to the course to learn.
I wonder how you feel about age discrimination. Old != bad.
I started using Vim when I was 14; I was the only one in the class who wasn't using an IDE. Vim (perhaps combined with a language server if you're okay with the complexity) runs circles around bloated IDEs like IntelliJ/VSCode. Unix combined with a tiling WM is the best IDE in existence.
The professor in question is likely doing the students a service by showing them the advantages of minimalism and function-over-form over the trend of bundling an OS with every "app". Many students today only feel comfortable using software that saturates their synapses with colors and animations; having to use Vim for a semester forces the good ones to realize that maybe, just maybe, function should come before form. Maybe 10k lines of C or POSIX shell solves a problem better than a VC-backed Electron app.
To continue your analogy, WordPerfect and DOS, unlike Vim, aren't better than today's tools. What would be an improvement is LaTeX/BibTeX for writing essays. Once I realized how much work was automatically done for me--from Chicago-style footnotes/endnotes and auto-generated ToC from headings, the time I spent formatting my papers dropped to zero. I would absolutely incentivize students to use these tools over "modern", bloated word processors.
What I was trying to say was that if minimal solutions run circles around bloated ones thousands of times their size, and when it takes a startup and two funding rounds to develop something that does exactly what tools did three decades ago less efficiently, then maybe Braithwaite was on to something:
> “It’s a curious thing about our industry: not only do we not learn from our mistakes, we also don’t learn from our successes.” -- Keith Braithwaite
(This is setting aside the argument as to whether Vim is a "dated" editor. Vim is an old editor, to be sure, but forget WordPerfect -- it's not as old as Microsoft Word is!)
I don’t interpret that as the college professor saying this is actually the best way to code, just that forcing students to struggle through it is a learning experience.