That's patently ridiculous. We know how to market auto mechanic shops. All the knowledge is there, you can even go to a library to read about it. Nothing about the industry has changed so drastically in the last fifty years that you have to throw out the book.

Small business marketing and economics are so simple and well-understood that your grandma can start a catering business, and, so long as she follows the formula, can guarantee she won't starve. She can listen to the banks and the accountants and the lawyers and be confident she's getting good advice.

Ask your grandma to start a website. Nothing about that space is well-understood to the point where she can have any reasonable amount of confidence in any course of action she decides to take. Sure there's forums, there's books, but the landscape changes so often that you have to treat everything as if it's already outdated.

It never fails to amaze me how often people immersed in technology seems to catch Stockholm Syndrome every time they think about business in this space. It's hard. The fact that there's zillions of choices makes it harder and not easier. The fact that you can do whatever you want makes it harder and not easier.