1. Word has automatic numbering, true, but it's not necessarily designed for the sort that was used in this paper.
2. From the article:
> Note added 2020.12.07: ... Each item in the list looked like a flush-left paragraph, like the paragraphs in this blog post, adjacent to the left margin.
They were numbering paragraphs, not line items, and lines that wrapped were supposed to be left-justified. I don't think this is a strawman.
3. MS Word would have a fit with skipping a number before "They" in the sentence above, and assigning number 3 and not 1 to this paragraph.
4. There are other cases when you need to separately label Article 1/Section A/Clause I etc. in a hierarchy; the numbered list tabulation and hopefully semantic Heading 1/Heading 2/Heading 3 styles and tables of contents in Word can handle this for your use case, but be prepared for frustration if you want something a little different than what the UI is designed to help you build.