The author raises a good point about page load times not really being minimized and lack of thought around good responsive design. However, I'm unconvinced about the rest of the arguments.

For example, he notes "The first rule in usability 101 is to give the end user what they expect." Maybe for the first year or two in the smartphone era it might have been acceptable to simply provide a shrunken zoomed out version of the site. The onus would have been on the user to navigate appropriately. Which... is a lot of work. My (swiftly getting older) eyes appreciate the larger fonts and readability that in theory a responsive design provides. I now expect to be able to read am article in portrait mode with a decent font size without having to zoom in and out. Maybe I'm alone but I would not be surprised if more users expect this now.