Many chemicals both in the detergents and possibly in water can cause damages to the machine. There are some other problems like hosepipes or other fittings getting loosened in the course of time. Improper electrical connections can also cause damages to the machine. No one can predict the problems that may occur due to moisture, heat, chemicals and electricity. Overloading of clothes also can cause damage to the machine.
Replacing parts does not lower the products standards. It is the same unit even enhanced and improved with something new. It can be comparable to a turkey filled with stuffing for Thanksgiving. It is the same fowl animal with something better inside. The outer covering remains the same despite changes inside.