As they explain in the article, a row-less layout with columns is quite common in the non-web world. They acknowledge that some people are arguing that it's not needed because nobody's using it (on the web). Nobody's using it (on the web) because it's not possible in CSS.
The argument is that the popularity of the layout in contexts where it's possible is a strong argument for enabling it on the web as well. This is not a layout that they just thought of and are trying to invent.
The argument is that the popularity of the layout in contexts where it's possible is a strong argument for enabling it on the web as well. This is not a layout that they just thought of and are trying to invent.