Most tweaks (Cables are not tweaks, since the system will not work without them) are designed to do one thing: reduce vibrations. Without getting into a big discussion about physics, vibrations prevent audio gear from functioning at their highest level.
The more these vibrations can be reduced or (not likely) eliminated, the better the equipment is able to sound. Vibrations come from the ground, and from the air, each of them have a detrimental effect on the sound. The battle for the last twenty, or so, years has been to minimize them. All kinds of items have been used with varying degrees of success. In overly simplistic terms vibrations are absorbed with items like Sorbothane or vibrapods, or dissipated with items like cones, and stands. Some work in certain environments, while others work better in different environments. The buyer needs to know what he is trying to accomplish when buying the different types of products.
Just like, not everyone will need an AC line conditioner, not everyone will need every type of vibration treatment.
Hospitals, observatories, and science labs have been the main source of understanding the effects of vibration. These places require accurate measurements to do their research, and small vibrations will have large effects on micro measurements in science. Again I hope I am not being overly simplistic in my discription, I'm trying to make it as understandable as possible, but everyone here is above average, so it should not be an issue.