Both concepts are valid.
A change of attitude in a performance aircraft with low total drag will have little or no effect on speed. Therefore power is best used to control speed and attitude to control the aiming point (ballistic approach) – whether it be derived from a glide-slope indication, PAPI or simply the runway markings. The technique will also overcome the adverse effects caused by wind shear.
However the use of power to control rate of descent and attitude to control airspeed (conventional approach) is essential when juggling an approach path for a short field landing. The aircraft is normally trimmed to a speed equal to or better than 1.3VS in the landing configuration. At fifty feet power is reduced and round-out commenced for a touchdown at minimum flying speed. If a higher than normal ROD is encountered the application of power is the only available option to recover from a high sink rate as any further back-pressure will probably lead to a stall!
For this reason students should be taught the conventional approach technique. Furthermore it is in line with standard descent techniques taught in every text-book I have read on the subject. Leave the ballistic approach for graduates to performance aircraft.