In Tripod Headstand the hands and head form a triangle.
In this position it is easy to feel how the arms work to help keep you balanced. With weight evenly distributed between the hands and head you need the arms to be strong to stay upright.
Also, if you feel your weight moving towards your hands you can increase the pressure of your hands to shift your weight back. If you feel your weight moving towards your head then you can reduce the pressure of your hands to shift your weight forwards.
In tripod headstand, having the weight centered between hands and head can make it easier to stay balanced