The value of that recommendation is rather dubious considering today's high-resolution displays that allow for smaller font sizes. 80 readable characters at 768p are not the same as 80 readable characters at 4K.
To my surprise the paper actually concludes that fast readers prefer shorter line length.
Edit: Usually books and newspapers are also more or less in compliance with this convention and those where around since before computers where a thing.
Columns work great for things like a navigation sidebar or an image grid, but it just doesn't play nice with long-form blog content.
Rules can be broken, but not without consequence.
Do people actually do this? I have like 10 tabs in a maximized browser window. Am I supposed to keep unmaximizing it and fidgeting with the width? Or am I supposed to just rip the tab out and have to deal with multiple browser windows?
I have a 4k screen. Most of the time I keep my browsers half width. For most sites it seems to be the best use of screen real estate. Even at half width that site's CSS restricts the width of the content too much, leaving a lot of wasted padding on either side.
Probably like 98% of the time, yes.
It's not an ultrawide, just a 27" 16:9 screen.
I find small windows to perform poorly on anything that's not just a simple document (gmail, hacker news, etc) because those require some horizontal space.