Author here. I tend to agree. But most people aren't "X" famous where "X" is the field they are trying to create a startup in.

In that case they need to find ways to reach out to users and early adopters without relying on their celebrity in that field.

Thus being able to generate intrest organically from people who really need what you have to offer - even if the volume of interest is initially low - is an important skill to know.