The issue with columns in web browsers is the variance in screen height. Clearly it would be worse to render an entire long-form article in 3 columns, forcing the user to scroll back up to the top of the page to start reading the next column.
This forces the designer to break the content up into multiple column blocks based on a target screen height... so now we have the same problem, only on a different axis.
This forces the designer to break the content up into multiple column blocks based on a target screen height... so now we have the same problem, only on a different axis.