Long answer - the vast majority of the time icebergs just sit there slowly melting and not bothering anyone. But every now and then, they tip or split into pieces. And when they do, you don't want to be anywhere near them. The resulting waves can be deadly.
And there is no way to tell when it's going to happen, especially if it's a piece of ice braking from under the water and suddenly popping up ( sometimes from under boats).
Even though cases like that are extreme rare, it's better to be aware.