I did webdev for a long time, so yeah. If you want the story, I was looking into guix on asahi and ended up on https://www.asahi-guix.org/ which didn’t load anything, so I checked the page source and noticed the element.
Thanks. Not sure what's with the downvotes. That was a genuine question.
(I used to do a lot of web development and probably know dev tools better than most people here. However I almost never look at the DOM of a webpage I don't own)
I frequently look at the DOM of webpages, so that I can bend them to my will.
There's always some things about practically all websites are frustrating. I fix that with custom CSS and/or Javascript that runs when I load specific sites that I use frequently. I can turn a cluttered site into a streamlined site for my needs. I also block a lot of ads, popups and other annoyances this way.
Text doesn't transmit tone well. FWIW I interpreted your comment as having somewhat accusatory intent, especially the scare-quoted "notice", for implying the author didn't just happen along his discovery and that he wasn't being fully truthful in his explanation of how he discovered this info.
I was sure you're going to take it in the direction of the relevant xkcd [0], so was taken aback that you didn't end it with something like "but today the pattern of divs is all wrong".