Hmm I don't know what to make of this, it seems like mostly a question of semantics of the scientific vs. casual use of the words attention span. The scientific use seem to refer strictly to the biological capacity to pay attention. But the laymen seem to report that they feel and act as if though they have short attention span. The science description of this phenomenon seems to be "short attention habits". So they argue that it is not about biological capacity, but the societal reward structures which enforce short attention behavior.
As a layman it is not particularly obvious to me, why they define attention span to relate to the capacity and not the habit or behavior in the first place?
Very interesting points, and I see your point between all five, although except maybe praepropere? while in theory i can see this helps syncronizing communities, especially people with different lives (such as families), to sit down for the same dinner ritual. But in practice I have friends and family some of whom 1) have very active lifestyles such as running to/from work, and so requires more snacks to keep stable energy levels and 2) they have different eating habits for other reasons such as avoiding the psychological effects of truly feeling hungry. In either way, we keep having shared dinner rituals, they just eat different amounts.
So i dont really see how the is a bad lifestyle or some ethical shortcoming, but just a rule to adhere to a specific social norm.