I feel awfully sorry for kids in school these days. Teachers must think everything they write is AI, considering they're still learning to write effectively and probably like to use bullet points, popular phrases like "dive into", and structured layouts that include introduction and conclusion sections.
As another comment (https://news.ycombinator.com/item?id=43105143) notes, some of the author's earlier blog posts use a different style of punctuation so I'm willing to bet that they might be using AI to help them write or reformat some of their ideas. I don't think there's anything wrong with that but without some re-edits to the AI text it will take on that distinctly AI tone.
Kids who are still learning how to write still have a tone/voice/style that comes across in their writing and I think that's the particular distinction being made here.