As someone that recently went through an introductory Japanese course in Japan, I don't find this much different than how it's taught. Or maybe I'm missing something? It seems like the article is trying to make the case that in romaji, you can split the letters and isolate the vowel (e.g. the asterix in the article's conjugation). But we were simply taught to change from the う- row to the い- row (u- row to i- row). I…
That said, part of the challenge to myself with this article was to allow someone to learn Japanese conjugation even if they have zero knowledge of the language (even no kana). So that’s another constraint influencing my choice. I also wanted to have the visual “gluing” throughout the article as an aid for intuition, so that’s another reason I used romaji.