The joint position is taken as the control point of numerous algorithms. And those algorithms have some function or parameters to put some offset from joint position to the control point. But many robotics people utilize DH parameter joint position decision because we learn this at lectures or in textbooks. And even DH does not guarantee a unique solution. Because the revolute joint can be placed at any point of the actuator axis. But this is quite a good feature for convenience. The joint position will be the same as with the instinctive point of the student who learns and solves the DH-parameter at school.
https://en.wikipedia.org/wiki/Denavit%E2%80%93Hartenberg_parameters
The joint position is taken as the control point of numerous algorithms. And those algorithms have some function or parameters to put some offset from joint position to the control point. But many robotics people utilize DH parameter joint position decision because we learn this at lectures or in textbooks. And even DH does not guarantee a unique solution. Because the revolute joint can be placed at any point of the actuator axis. But this is quite a good feature for convenience. The joint position will be the same as with the instinctive point of the student who learns and solves the DH-parameter at school.
But this is not much matter stuff for now.