Squash and stretch is not implemented with scaling. In fact, for any rational animation system (meaning one that a non-engineer digital artist can actually use)

Squash and stretch is not implemented with scaling. In fact, for any rational animation system (meaning one that a non-engineer digital artist can actually use) the use of scaling is simply not available in the system. Scaling in a hierarchical animation system is a guaranteed method to fuck up an untold large number of additional systems such as the physics/dynamics associated with the scaled character as well as any geometry attached to the character, as well as any sub-systems which use the now-scaled character for decision triggers. There are simply too many inter-dependent systems that rely on aspects of the environment, such as the scale of objects, to remain consistent for the entire illusion of a consistent world to be maintained. Speaking from experience: I've written dozens of 3D animation systems for games and film VFX. I've been writing 3D animation systems since the 80's.