Why do people dock Rottweiler tails?

Why do people dock Rottweiler tails?

Rottweiler was always known as a working breed, at the time this breed was developed to prevent their tails from being grabbed by assailants and to prevent problems which a dog could have pulling the carts (such as the tail getting caught in wheels of the carts) people docked the tail of their Rottweilers. 

Nowdays even though in some countries of United States of America and in some parts of the world, Rottweiler isn't known as a working breed but more as a guardian dog, people still dock rottweiler's tails for tradition and aesthetic reasons... 

Since tail docking is done at such a young age (1-3 days), they feel little to no pain because the nerve endings are still undeveloped...