> Humans are insanely smart and capable, treat them that way and good results occur.
My experience isn't quite that. While most humans can be capable when they want to, in typical situations they often don't and aren't. People who have put in years to become proficient in mainframe terminals aren't representative people in a typical situation; most people (myself definitely included) perform most daily actions on autopilot.
And autopilot rely on consistent environment. Full focus isn't sustainable. Training and practice rely on this capability, ingraining something in muscle memory so you don't have to pay that much attention. When someone wants to fill a form or process some data, the less he/she pays attention to each action, the better it is.
EDIT
And that's why I like Vim and most TUI that much. I don't need to follow the cursor or wait an abitrary amount of time because "reasons". It's all muscle memory, and my attention is more on what I'm trying to do than how I'm doing it.