I am not a medical professional either.

Our cub scouts had a first aid class and the instructor talked about using a tourniquet and including it in a first aid kit. I must admit it concerned me a bit that he seemed to be advocating their usage. On the other hand, maybe he thought since he was teaching a group of scouts (I am sure in his mind he assumed cub scouts = boy scouts) that some last resort, life saving wilderness first aid techniques were in order (or maybe he teaches it in ALL his first aid classes -wishing now I had asked him).

It has always been my understanding that a tourniquet is an absolutely worst case, last resort, the person will die if the tourniquet is not used kind of thing. In that context it would be worth including in a kit and learning about in a first aid course.