I'm curious how the smaller screen affects productivity. I've had the primary responsibility for building applications with associated web services and tackling that on a 15" Retina Macbook Pro was, while possible, hardly ideal and certainly not what I would call "enjoyable". It was by temporary necessity and it was a relief having a large external monitor attached. Jumping between applications gets old pretty fast and turns what would otherwise be a smooth flow from one part of a task to another into nearly a full context switch.

As an aside, when I see "simply", "of course", or "just" (or, for example, hear it in a presentation) I get concerned since those are abstracts of highly variable possibilities that could otherwise be interpreted as "your mileage may vary". Ergo, the relevance could drop off precipitously, leaving little more than a passing anecdote.

That's not meant as a jab at the author as I appreciate them outlining their experience as it provides useful guidance. (And I'm probably over-analyzing it...)