There is generally more than one way to skin a cat, as the saying goes, and the concept of what controls what is just something that helps us get our thinking straight when we fly.
I've always found it useful for climbs, cruise and descents other than final approach to use attitude for airspeed, and power for rate of climb/descent. Naturally the two affect eachother, but it gives you an effective control technique to use to fly accurately. For example, say you wanted to descend at 140 kt and 500 fpm; set an appropriate descent power and attitude for the type, adjust the attitude to get the right IAS, see where your ROD stabilises. If it's too high, add an increment of power - you will then have to raise the attitude a bit to maintain the speed (in practice, you'd do both at the same time). So it's just a way of thinking, rather than a black/white argument.
For finals, though, you're aiming to fly a particular glide path - I imagine a set of rails leading from an appropriate 'gate point' at the commencement of final (height, distance out and speed), and use attitude to fly down those 'rails', now adjusting IAS with power.
Some people do this differently; ie continue to use attitude for IAS on final and power for where they're going to hit the ground. I like the preciseness of setting aim point directly with attitude, but it's just personal preference; you say tomayto, I say tomahto kind of thing.