Many people are quick to say that certain exercises, like the behind-the-neck press, will cause injuries. Of course, anything can cause injuries, especially if you're doing anything worthwhile or rewarding. The trick is to make your body physically prepared to cope with the demands of training.
With the behind-the-neck overhead press, the risk simply comes down to your posture. Bad posture? It's not the best choice for you yet.
Prior to the early 90's, hardly anyone used scientific references to support their notions – not in real life and certainly not in the magazines. You just said what you believed and most of the time no one questioned you.