Please explain why that statement is wrong and how you operate the aircraft not using those basic principles?
It's wrong in a few ways, especially for prop aircraft.
1. In the mushing regime, nose high.
2. At high cruise speeds (try raising the nose, speed will decrease, even at max throttle)
Finally, it also give the impression that pointing the nose up and shoving the throttle forward gives a climb. Not always.
In short, it's hopelessly inadequate for all but a very limited range of speeds. Fine if you're flying an F16, but useless in a light aircraft. A student, if given only this 'rule' would stall and spin, in my opinion.