If you will, please view the suspension links as a four-bar linkage, i.e., a parallelogram. If the stud of the lower ball joint is made longer, that side of the parallelogram is also made longer, and when the linkage is deflected (bump & droop) the arcs through which the ball joints move are changed from the original configuration. As a result, the camber curve(s) is/are also changed.
To lower the chassis without altering the camber curve, raise the spindle on the upright.