Years ago, the police around here told people to do that.It was only to save the police some work.They could check with the ss# owner easier than checking if the serial number was stolen.In my opinion it didn't help, for the reasons mentioned above;plus I don't think it is illegal to remove a ss#, but it is highly illegal to remove a manufacturer applied serial number.The police should think a little bit before they tell people to do things.
Mike