Although preventive maintenance isn't the norm for most businesses it's much more cost effective than reactive maintenance. Had the customer set a planned maintenance program they may not have lost the bin full of ice.
Proper defrost is very much necessary for long system life. if the system freezes over then liquid refrigerant makes its way back to the compressor eventually taking out the compressor. Age has no priority here, a new comp will be destroyed as easily as an older one.