I think that the article makes a strong case, which meshes with my personal experience as both student and teacher, that word count ranges aren't always a good way to convey the expected scope. If you're a regular contributor to a magazine, with a well-defined and professional style, then a target length can be a reasonable metric. For students in their formative years, such a metric can lead them astray.
Whenever I teach English writing, I never attach word counts. I tell them to write on one side of an A4 sheet. The students use less fluffy language, handwrite more legibly, and leave plenty of whitespace for me to write comments. It's easier to mark, as I just need to scan the sheets without turning them over, sorting them into order from best to worst.
You also should teach aspiring writers about the new digital ways of earning money. I still see so many people who are in the "I am a journalist / I am a writer" and so on camp relying on old thinking about 'but I only get paid by that'.
Slowly we will change that.