Reason for a tripod or 3 feet under a piece of gear: (1) Easiest to level; (2) The weight of the supported object will be evenly distributed among the 3 pods, once the object is level and if the tripod is properly implemented, (3) Fewest paths for vibrational energy to travel from the shelf or stand into the component. These are not trivial advantages, but extreme stability is not among them, as others have noted.
Tripods as turntable or component base?
Perhaps one of you who is into photography or owns a camera store can try this experiment. Since the tripod is the most stable base (ask any photographer or physicist), has anyone experimented with using them as component bases? All the best turntables and many other components now have 3 legs instead of 4 for that reason. One school of thought says heavy tables for turntables are better (less amplitude of motion for given energy input); others say not (energy storage, pickup of airborne sound energy). The people who used to market Linn specifically recommend flimsy tables (!) but they were fruitcakes. How about taking three tripods, setting up one under each foot? A cheap experiment if you have the tripods... Your colleague in science, hifigeezer