The cost of one backup set alone would come to more than the entire machine - plus labour. As every manufacturer knows it is an absolute law of physics that every hard disk will fail , and that failures can happen at any point in the life of a machine . As every user knows, major hard disk failure usually means total catastrophic loss of all data. That can mean the end of a small business or a personal career. But theft is commoner than failure.
Most new users are naive, and assume that their machines are complete.
But a machine without a proper backup device is a disaster waiting to happen. Manufacturers tell us that recovery is easy - just insert their software CDRoms and it all happens automatically. And the same with any other bought software. This is a wicked lie. Every piece of software you buy inserts unique code into the registers of the machine to run under Windows 95, and many programs require hours of fiddling about with special settings to make them work properly with everything else.