User Interface Design for Programmers – Chapter 8
Human aptitude tends towards the bell curve. Maybe 98% of your customers are smart enough to use a television set. About 70% of them can use Windows. 15% can use Linux. 1% can program. But only 0.1% of them can program in a language like C++. And only 0.01% of them can figure out Microsoft ATL programming. (And all of them, without exception, have beards and glasses.)
The link points to this image:
Guilty as charged.