I agree that sorbothane and similar materials are mostly a poor choice for most audio applications, because they have hysteresis and are not at all linear. The issue at hand is that vibration of equipment, components, wires and signal connections can affect the electrical signal which carries the music. A stated objective is usually to isolate or minimize vibration to minimize these deleterious effects. Vibration is generated from the loudspeakers, especially via acoustic energy, and is potentially correlated with the music signal; but can also can originate from equipment including power supply transformers, or from external sources, where it is uncorrelated with the music signal.
I assert that vibration can be reduced, but never reduced to zero. When the vibration originates from the music signal itself, it is essential that the moving system be linear. This hopefully low level of vibration, if it alters the music signal in a highly linear system (such as with microphonics, for example) can add a bit of “reverb” that is relatively inoffensive. If the system is non-linear, then the vibration can be non-linear and contains (a term I use) vibro-mechanical distortion. The non-linear vibration components, if they alter the music signal, introduce non-linear components into the music signal - distortion, which can be offensive.
So, in my opinion, non-linear materials such as sorbothane should not be used to isolate or reduce vibration which is correlated with the music signal, but may be useful when the vibration of concern is not correlated with the music.