See below ;)
He means purely for practice purposes (seeing what the difference is).
Right:
Obviously power and pitch are used in conjunction. Having said that, pitch is mainly for vertical speed and power for speed. In prop planes this balance is well in the other direction in some cases, as the prop airflow can create additional lift (you definitely do NOT want to cut throttle on the flare in a B-17 for example.).
For jet powered aircraft this is not the case (unless you'd have a wing behind the jet exhaust :P ).
Example time (airliner, but also applies to our jet, but less exagerated): imagine you arriving at your minimums in an approach to land and you need to do a go-around (for whatever reason). The idea is that you cut your vertical speed immediately. If you *just* increase power (power for vertical speed method), you'll slam yourself into the runway. Obviously, you need to pitch up (i.e. pitch movement!).
When you pitch up in a jet, the first thing that happens is that the aircraft starts to climb, and thus loses airspeed.
When power is decreased (while keeping the same pitch, no pitch control input and disregarding any pitch-power effect which is very aircraft specific) the aircraft will first lose airspeed, will tend to nose down a bit. The only way then to keep the speed is to pitch down, this increasing the descent.
Not sure if I've explained myself properly, hope it helps though :P