When pitching to a new client, you often carry a deck of slides with you to cover your uncertainty. “At least I can lecture about X or Y and flood the prospective client with facts”. In the end what makes the sale is not the lecture about you, but the dialogue about the client’s issues.
It also works for me and my presentation design business. A quick email conversation when a prospect asks “What do you charge and send us a link to an example of your work” is less likely to convert into a project then a half an hour conversation about the actual story.
Most of the times, clients think they are looking for slide make-overs, while actually they need a story redesign. Stating: “I redesign stories and look here is where I have done it 500 times before” does not make the same impression as doing the actual thing on the fly.