Just because it's the default doesn't mean it's suitable for reading and it was never thought of being that.
Then there's the separate issue of overlong paragraphs, which is simply a sign of poor writing (again making the text less accessible), unless you're trying to argue that the use of fewer <p> tags makes the page faster to load and render?
Now, I do wish that browsers had saner default styles, so one wouldn't need even that single line of CSS, but that's not the world we live in, and for whatever backwards-compatibility reason we're stuck with how things were in 1995.
I don’t understand though. Times new Roman and clones of it are very readable fonts. It just doesn’t look like short form marketing material.
I have this 16:9 screen. I'd like to use all of it, thanks.
(I'd suggest more than 50 but not a whole lot more, not nearly enough to fill a normal size screen.)
Absolutism on either side of this debate is purely ideological and does little to serve the user the best possible experience.
Instead, I will focus on more objectively measurable aspects such as flexibility and ergonomics. You may be getting the most flexible reading experience, but you are getting the most ergonomic reading experience. You also have to put in up-front work to get a better experience, or rely on tools like Reader mode.
If that's what you prefer, that's fine. If you weren't aware, in most browsers you can access the menu bar and navigate to "View -> Page Style", and set it to "No Style".
Then you're free to add whatever styles you'd like on top. Meanwhile, the casual, less technical, non-designer user can still engage with the content in an accessible and easily parseable manner.
You can’t read a long paragraph in reader mode?