The first cake mixes were complete failures because they had all the ingredients in them. Housewives felt guilty using them, so they wouldn't buy them. When someone realized this, they made mixes that needed to have oil and eggs added - and their success was assured.
This is a good example of how marketing evolved over the years. They've come a long way since then - at our expense. Pun intended.
You can now buy cakes, pies and more ready for the table. All you have to do is thaw them out. My, how much we have learned.