While arguably shorter lines were easier to set and maintain by hand, both hand typesetting and Linotype machines could certainly produce lines of text longer t

While arguably shorter lines were easier to set and maintain by hand, both hand typesetting and Linotype machines could certainly produce lines of text longer than a typical newspaper column -- and they did: look at any book without columnar text produced during the same period! I think you're right about it being a way to deal with a physical limitation, but not of the physical type -- rather, of the physical paper. If you divide the page vertically into two or three columns (for magazines) or six to nine (for broadsheets), you get an extremely flexible grid to use for fitting stories around one another and around photos and advertisements. Text could be a single column wide or two or even three columns across; headlines can run across just a column or two or across the whole page; you can always find somewhere to put that story that continues from page 1A.