Wonders for YOUR readability. Other people have different viewports and screen sizes/resolutions and that would most likely interfere with some of them. Some people might even prefer dense text and long lines (doesn't bother ME).

As others have pointed out, you should be able to adjust your browser to get the reading experience you want. Turn your tablet vertically if reading in landscape. Open current tab in new window and make it as narrow as you want. Or have smart browser extensions that do it automatically for YOU.