Sounds like the author got called out for not capitalizing the start of her sentences[1] and decided that, if HN readers want capital letters, they will get them.
Which is funny because if you engage Reader Mode in the browser, everything becomes proper except sentences, which still start with lowercased letters for some reason. Names are still properly capitalized. It's truly bizarre
[1] https://news.ycombinator.com/item?id=39027187