The article just talks about web-reading, and how more and more webpages are being responsive (for mobile reasons) in ways that actually now optimize sites for vertical orientation over horizontal.
However, from a coding and word processing* perspective, vertical layout is a bit better, too, as it allows you to see more of the text and the text's context, than horizontal mode does. Thus, most developers who pay attention to such things do use both, as the first 5point comment suggests above.
In fact, that was the actual vision of the PARC crew that invented GUI and WYSIWYG back in the 70s: the Xerox Alto workstation they created did have a vertical monitor, for this very reason: the idea was that if you were using a word processor to show you a page's layout, seeing the whole page on screen was the desired effect. They discovered it improved coding productivity once they were using the workstation to produce the software.
(that said, it is NOT better for spreadsheets or powerpoint, or database-editing tools, so there we are.)