I've been taught both ways (civl and military). The primary difference was about thrust to weight.

Light aircraft are generally pretty low-powered. Often times, the only way to speed up is by lowering the nose.

High-performance jets (fighters) generally don't have that problem, although when maneuvering well beyond the stall, even burner won't accelerate in some circumstances. Civil jets can easily have the same problem. (Think heavy airliner, fully-flapped, slow on final...thrust isn't totally effective to speed up if on the back-side of the power curve.

In any airplane, the real answer is: it's both. It depends on how far on the back-side you are, and whether there is adequate thrust to speed up. I primarily use throttle for speed, pitch for vector control...unless I run out of throttle.