I believe that doctor's did not always know the full effects of a medicine many years ago. Side effects can be added as people experience them, thus adding to the knowledge of what the drug can do. Problems that show up with getting off of a drug can then lead to the dilema of either getting off with lots of problems or leaving things as they are. My mother took benzos and later on she developed a bad heart due to other reasons. The doctor thought going off benzos would be worse than staying on them.