It would be more precise to say those are the capabilities of one of the systems that comprise the brain. I think it's a mistake to lump the speed of perception in with the speed of cognition. To put it another way, pointing to the superiority of a gigabit ethernet connection is probably misplaced if it's connected to a microcontroller board running with a 5 MHz clock.

teaching the average person to use a new piece of software is near impossible without utilizing their incredible brain power for visual recognition

This is where I fear GUI enthusiasts often go astray: conflating everyday usage of software with the experience of people learning to use it. It is very useful to examine a light switch when you first encounter it, for example, but people quickly adapt to the common use case of flipping the lights on when entering a room without having to look at the light switch. Or in terms of the original article, most of the usage of a mail program is reading and writing messages -- an area where the advantages of icons, buttons, and menus are debatible.

BTW, CLI user are using their visual systems as much as GUI users are. CLI users are merely using a more structured format for their visual input.