BLEH! This pitch controls this, power controls that, is just crap. If pitch controls airspeed, go to the end of the runway and pitch down without adding any power, how fast do you think you will go.
It is a combination of the two, if the airplane is trimmed for the airspeed (say Vref) and you are high, you pull the power out and the airplane will seek that airspeed, but it won't do it smoothly so you have to control pitch to get it where you want.
I used to have my instrument students fly an ILS with nothing more than rudder and power, trim the airplane for 90 knots and fly the thing in without touch the yoke, in that case power controls everything.
Don't get wrapped around the axel about what controls what, just realize both inputs (pitch and power) need to be made to make the adjustments smooth and understand how adding one effects what you need to do to the other.