The ancient Egyptians believed that your soul split into two parts after you died. One part, the Ba, flew off every morning to keep watch over your living family. The other part, the Ka, flew happily off to enjoy life in the Land of Two Fields. At night, both the Ba and the Ka returned home to your tomb to rest up for the next heavenly day.
If something happened to your preserved body, or if your name was not written down somewhere, the Ba and the Ka would get lost. They would not be able to find their way home to your tomb. You would disappear. Forever. You would not be able to watch over your family or to enjoy your afterlife.
That's why the use of a cartouche was so popular. A cartouche is nothing more than a name plate attached to your coffin. A cartouche made it easy for your Ba and Ka to find their way home.
That's also why grave robbing and the destruction of mummies to get at the treasures hidden inside the folds of wrapping was such a vile crime in ancient Egypt. Grave goods could be replaced. But there was nothing your family could do if robbers disturbed your preserved body. The ancient Egyptians believed you would be lost forever. There was no worse crime.