The smartphone represents the death of ergonomics.
A featureless and unremarkable slab of plastic, aluminum and glass. If one is to think that form follows function, then the function of an object should be obvious from analyzing its form. The smartphone defeats itself, its shape says nothing of what it does. Is it for taking pictures? is it for writing? is it for reading? is it for communication? When every answer is yes, then what is it good for? It's not particularly good at any of those, it is just good enough. The most basic of the common denominator, an abstract rectangle, a basic black mirror of nothingness.
Ergonomics are about shaping an object so perfectly to its function and to human biomechanics that its use becomes spontaneous when the object is used and it doesn't hurt or harms the user. “The maximum of comfort, security and efficiency.” The smartphone is not any of those, for any of the things it does. It is awkward to hold for a call, it is strenuous to read or even watch media in, it is uncomfortable to hold to take pictures with, touch control are inefficient for gaming or typing.
There's one thing the smartphone is though, it is small and it is portable. That's it.
When you experience the functions of dedicated devices, the shortcomings of the smartphone show up even more evidently. Holding even a hobbyist camera, reading on an e-ink screen, playing games with an actual controller (or mouse and keyboard), writing even on a basic mechanical keyboard. A smartphone will never compete on that level of tactility and comfort.
The smartphone is the death of ergonomics.