Your comment was very puzzling to me, as I couldn't figure out what kind of misunderstanding about this article would prompt a comment such as this. But finally a possibility occurred to me: perhaps you think the point of this article was simply to say that there exist "systems that defy detailed understanding". It is possible that one could think that, if one went in with preconceived expectations based only on title of the post. (But this is a very dangerous habit in general, as outside of personal blogs like this one, almost always headlines in publications aren't chosen by the author.)

But we all know such systems already: for instance, people! No, this post is a supplement/subsidiary to the previous one ("Computers can be understood" — BTW here's another recent blog post making the same point: https://jvns.ca/blog/debugging-attitude-matters/), carving out exceptions to the general rule, and illustrating concretely why these are exceptions (and what works instead). It is useful to the practitioner as a rule-of-thumb for having a narrow set of criteria for when to avoid aiming to understand fully (and alternative strategies for such cases). Otherwise, it's very easy to throw up one's hands and say "computers are magic; I can't possibly understand this".

(The point of the article here is obvious from even just the first or last paragraphs of the article IMO.)