I found that article quite poor.
As
photoptimist rightly pointed out, any definition of what is a "normal" lens must depend on some baked-in assumptions about how the photos are most likely to be viewed. It also depends somewhat on human perception, as the scene in front of us that we pay attention to will vary depending on circumstances and subjects, but it is usually much less than the actual 180° FOV of a healthy set of eyes.
Aside from that, the conventional photographic wisdom (oddly never mentioned by the Atlantic article) says that an ideal normal lens is equal in focal length to the diameter of your film frame or sensor. That's an arbitrary rule-of-thumb, but it's one that has worked reasonably well in my experience. For 135/FF format, that would make 43mm an ideal normal lens. Guess which camera maker actually produces a 43mm lens?
Something else the article never mentioned: While 50mm became regarded as the standard normal lens for 135 format interchangeable-lens cameras (both rangefinders and SLRs), that doesn't seem to have carried over to other types and formats of cameras. For many of them the choice was 40mm (or equivalent, depending on the format).
I've become rather fond of the 40mm lens, myself. I almost never reach for the fabled "nifty fifty" if there is a 40 available instead.