To be clear, the rotator cuff is a collection of muscles and tendons that hold the arm ball in the shoulder socket and provide support. It is not the ball and socket arrangement; it is not bone.
More strictly, the cuff consists of just four supporting tendons, but to build a rotator cuff refers to strengthening the muscles underneath the deltoids responsible for internal and external rotation.
Will hypertrophy and strength of the deltoids increase the resistence to injury of the rotator cuff?[/quote]
Not in and of itself, but certain delt movements stress rotation more than others. Side raises, not at all. Dumbbell pressing, a bit more.
Certainly you can strengthen the muscles that hold the joint in place, and subsequently their resistance to shock. That’s one component of joint health.
As above, they’ll strengthen the muscles and tendons that compose the cuff. But the cuff is only part of the joint.
Really, we’re digging too deep here. Cable rotations take very little time to do. Add them to you chest days. Focus more on the external movement.