Part of it maybe that most people who hurt their shoulder and do not go to the doctor *assume* its a rotator injury. I did, suffered with it for a while and when I finally went to the doc it turned out to be a problem with my biceps tendon. I did manage to screw my rotator up about a year later. Physical Ther. I went to said that the reason people get injured in that area is a lack of proper support for the joint, meaning weak muscles around it and doing exercises that put the joint in an unnatural position like casualbb listed above.