Earlier quoted context omitted.
for me, that's way worse, I much prefer to get full width, on my 32 inch monitor, it looks nicer on the default website, and fits way more stuff without needing to scroll. If I want a similar layout for "reading" I'll just use reader mode in the browser and get a very similar layout.
To each their own I guess, but to me you just described a terrible reading experience. Filling all available space with content may sound like a good idea on paper but columns of text should really limited in their width - that's just very basic and commonly agreed upon typography best practice.
except, that applies if you are reading something top to bottom, like a book. That's not what I do on wikipedia, I scan for information.... and it is much easier to do that in wide format. What you end up actually reading is a paragraph or two. As a speed reader, I read in chunks, and in wide format it's actually not that bad, its not a wall of text. Most paragraphs end up to be 3-4 lines long and are naturally chunked by citation notes. I find it really easy. There is no one rule of typography, there is general guidance, but context matters. If in your head you've translated that to a "rule", you are doing it wrong.