The explanations aren’t themselves incorrect — there’s certainly low-pass filtering, pre- and post-echo artifacting and so on, and these reflect in the waveforms — but to reference a waveform and to say “this sounds bad because it looks like this” doesn’t really hold water. Visual differences are not necessarily audible differences, which is the fact psychoacoustic encoding leverages.

If an encoder’s design goal was to produce visually-comparable waveforms, a different approach would be used.

> In fact, CDs can only replicate frequencies below 22kHz and even that's within the hearable range of many (mostly younger) people.

There is no useful or meaningful content above ~18 kHz (aside from dither) on most recordings. There may be exceptions, but by and large, on real music recordings, the information above that frequency isn’t valuable, and is the among the easiest things to discard.