Am I missing something or did the anecdote at the beginning have nothing to do with the rest?

As I understand it, the author was sharing the story to convince the audience he was a good writer and, thus, we should value his opinions on how to write non-fiction.

No you are not missing anything. This is a more recent bait-and-switch method of writing articles. I'm not sure where it comes from but if I had to be extra pessimist, I'd say it is a trope among failed writers. Sometimes they use narrative devices that work best in novels, but they end up being applied to normal every-day articles and the result is something that seems out of place.

Arguably if HN is to use LLMs to curate and administer submissions and comments (which it has been doing already), one would hope they can short-circuit this for all of us and scan the article/blog post, providing a summary directly underneath the submission/comment reply box. Reason being is, a lot of the time many paragraphs are spent belaboring one or two points that would best work in a tl;dr way and jump over these narrative passages, framings and backstories that serve very little to the points themselves.