For Engelbart, simple user interfaces were beside the point. At one meeting
of the Augment programmers, he posed the question, ``When NLS is complete,
how many instructions will it have?'' He went around the room and asked
everyone to answer. They were, of course, all wrong. The right answer was
that NLS would eventually have fifty thousand instructions! That would
require learning a language a significant fraction the size of English.

(John Markoff -- What the Dormouse said, pp. 200-201)


Tesler (Larry Tesler) believed that modes made learning too difficult for
unskilled computer users. He disputed Engelbart's view that the leverage
the computing tools would provide would be so great that the time spent
mastering a complex system would be justified. Engelbart's view was that if
people were willing to spend three years learning how to speak a language
and ten years learning mathematics and years learning how to read, they
should be willing to spend six months to learn how to use a computer.
That's ridiculous, Tesler thought. You should be able to learn how to use
a system in a week.

(John Markoff -- What the Dormouse said, pp. 244-245)