The break in period is mainly to seat the piston rings to your cylinder walls properly. In the engine the piston rings rub against your cylinder walls constantly, the tolerances are very tight.
Improper break in can mean the rings wear down too much and that tolerance widens up meaning that gasses can escape around the side of the cylinder and into the crankcase. Also on the flip side, oil can make its way into the combustion chamber easier causing excessive oil consumption.
Can’t say I agree with Mercedes over Audi/VW. Their new products are total shit