Surely, the better the speaker the better ALL cd's will sound
and not the opposite no?
How about an analogy. I think Kinn is just trying to convey that a sharp lens will show every pimple and wrinkle whereas a soft lens may complement better some portraits. "Better" depends what role you expect from the lens. Perhaps a portrait of a face will look better with a soft lens but a close shot of a bird might look better with a tack sharp lens.
FWIW: ATC will not hurt a recording but they are certainly not kind to a bad recording - you will hear errors in the mix, splices, odd changes in reverb, volume level adjustments on certain tracks, certain instruments and between tracks, microphone issues and audio compression on many modern pop CD's will tend to sound harsh. There is no denying that ATC are not for the mainstream type listener but they have their niche in pro environments and with some audiophiles.