[presentation]

I think also that anyone who's spoken Japanese for a while already has internalized that "si" === "shi" because there literally isn't the sound "si" in modern Japanese, as the other commenters mentioned it's often romanized both as "si" and "shi" in daily life, if you typed "si" into a keyboard it renders し, it goes on. The original comment on this thread includes one such person who literally didn't follow why "si" is wrong, and I felt the same way too as a long-time Japanese learner. It's a very "copy paste Western language concepts onto Japanese" way of conceptualizing the language, which is IMO a great way to set oneself up for great struggles when trying to learn a language that is structurally different, because it's not the right mental model.

[danabramov]

I’d normally be with you and I call this out as a concern purists would have my article. I’m doing something differently here and maybe more daring — the conceit of this article is that you can learn the entire system in one evening with no prior knowledge of Japanese at all. In that case I think the “s_ + i = shi” is as fine a pedagogical moment as any to introduce why the hiragana table matters. And for readers who already know it, I assume they won’t actually have a problem following the content, setting aside the pedantism and the annoyance at someone seemingly “teaching in English” and “copypasting concepts”. Like I get what you’re saying, I just think that it’s okay to break the rules for what I’m going for here.