One way of looking at this is to take the following guideline to apply at the article level as well: "Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize." (https://news.ycombinator.com/newsguidelines.html)
The idea on HN is to have curious conversation. For that, a better practice would be to bring in the most interesting bit from an article, or the bit that creates more interesting responses in you. If an article creates no such responses in you, then the way to use HN in the intended spirit is to look at at different article instead.
The author isn't and never claimed to be a historian. Their bio on Atlas Obscura says "I'm a senior editor and writer at Atlas Obscura, bee steward, mead maker and veteran of karaoke in Antarctica."
Probably better not to bother next time.
If the new bride (14yo) can read such a book then she is not a peasant. If the family owns a book then they are several tiers up again. Anyone reading this book therefore has at least one servant. If they do, that servant may well be a child even younger than the new bride (12yo). Such a person definitely cannot read. This is a book for the master or lady of a 14th century household speaking to their servant. Mansplaining is expected.