You are right it is partially true... partially wrong.
In sound, particularly music, tonal quality is not something that can be quantified. There are secondary frequencies called "beat frequencies" that are the result of one frequency harmonically adding or subtracting to another frequency and producing a third (or even more) frequency that adds to the tonal quality and overall sound. Some of the frequencies that produce audible beat frequencies are beyond the range of normal human hearing. If the high frequencies are missing in the reproduction, the beat frequecies that add to tonal quality will also be missing... resulting in an obvious perceived difference in what the listener hears.
So that's why AAC sounds so much clearer, depite years of concerts and a car accident making my ears not hear as well as they used to. Thanks.