I'm thinking the same. But one of the other repliers pointed out specific ingredients and ratiod that are hard to reproduce, like gelifiers and specific leaveners.

My grandma would have scoffed at using cake mix, but she was coming "from the land" and "during", and anything prepared in manufacture was the devil. Her cakes were so much better than anything premixed I've tried. I also think know I just borrow from my own experience to evaluate what I consider to be grandma-like ; my judgment is highly subjective and probably biased by hallo.

We sometimes buy premixed when we're lazy, there's nothing wrong with it, but it feels like cheating. We love buying premixed chocolate chip cookies, and making one giant cookie in a dish - for whatever reason I'd never do that witg my own mix.