Not to mention that on the desktop, the text is literally only quarter of the screen. Add that to the very frequent interrption bars, you are in for a very long scroll while reading
A quarter of the width? Well, naturally! The optimal line length for readability is somewhere in the 50-100 character range. This is one of those things that is actually backed by empirical research (lots of research... experiments in readability are cheap and easy to conduct, and people have been doing these experiments for a long time). The width of lines of text in tweets is on the shorter end of that range.
Hacker News, for example, is an example of a site with poor readability. The text is as wide as the window. To address this deficiency, I open Hacker News in a narrower window. It's still harder to read.
Not with CSS, their markup is impenetrable. You have to have another site scrape and reformat the content. Shameful.
Because it's highly that even if it's correct in aggregate, there will be outliers that the opposite is true, and they'll benefit from different formatting.
That is, even if it's right, it might still be wrong for them. So the question being asked is, why is it made so hard to change?
Like, you're talking about "what's right for them" as if that's supposed to pull my heartstrings, but the grandparent even literally said "I am going to re-phrase your question negatively", it's not like they're going to magically be convinced or actually argue about any readability metrics in any kind good faith, it's literally just a reflex. I wouldn't waste my time defending it on some egalitarian principles or whatever.
Only on a small screen. An HN `div.comment` has a `max-width: 1215px;` rule.