Chicken is extremely quick, and can propel a fast flurry of strikes, on any surface. The successive strikes have a firm foundation in an internal moving root.
The momentum of the whole body's weight is leveraged from the ground, and continuous with the arm movements.
All moves carry the force of the momentum, which is not possible with any external method including folding of a move (a full arm folding into an elbow strike). A folde move only continues the momentum of the limbs, not the whole body weigh and connected momentum. Externals lack the foundation of a moving root.