This is then followed, as you move forwards, by a distinct crossover of the hands and forearms as the club is released through impact - thus maximising the burst of acceleration on the ball.
If you turn your body back and then forwards without this wrist hinge then the clubhead speed is much slower. If you keep the hands passive, the clubhead does not travel far enough to generate real speed.
Without wrist hinge you are limited to the speed of your body turn. However, when you allow the wrists to hinge on the backswing and then unhinge towards impact you add a real zip and acceleration.
Remember though to keep the upper arms and shoulders passive. You have two gears to develop club head speed: body turn and wrist hinge. Active use of your large arm muscles just slows you down and will likely through the ball off track.
So, in the golf backswing, you need to keep the control triangle shape of your arms and hinge the wrists.