I agree any distortion is not good.
Music is not a simple sign wave. It usually is a collection of harmonics. 1, 2, 3, 4x, etc.
Harmonic distortion form a amplifier that adds to the harmonics content
aligned with the instrument is very hard to hear. Adding energy at the harmonics, increases the sound level, sounds louder, and thus your ear may think it is 'better'.
https://gabevee.tripod.com/harmonics.html A 0-distortion transistor amplifier, while not adding harmonics in normal operations,
when over driven will add energy at frequencies not aligned with the music. This is easy to hear the distortion.
Amplifiers should never be over driven. YES. Sitting in you living room listing to caned music---YES. In a live consort there is never that much ceiling. That is why I have limiters. Limiters in mic inputs, limiters on power amps and on recorders. I know limiters add distortion but that is very small compared to the distortion of a power amplifier out of control. If you have ever heard FM, CD or tape music you have heard the effects of 'limiting' and 'compression'.
I have never found any two Audio Gurus that agreed on everything (anything). I expect no to little agreement here.