What I've found in my career is several issues between supplier and customer, whatever the configuration may be: 1 - the supplier is producing something that they've always produced, how they've always produced, for who they intended it for the day they opened their doors; 2- suppliers never take feedback as constructive and cannot separate their person from their product and too that end - will never fire a customer that costs them more than they're worth; 3- suppliers that strive for excellence have great ideas that they are emulating from others who are successful but are quickly demoralized by a lack of or variable budget to accomplish those ideas in the form they appear.
What's great about Raving Fans!? The story permits you as the supplier to say, stop - take a breath- what am I doing - is it what the market wants or is it what I think they want, how do I reconcile the two and can I deliver it? If not, I'll pivot and say goodbye to what costs me money and instead put my effort into CONSISTENCY. This is so often overlooked in any customer relationship - customers want at the very least a steady eddy - a stand by. Once you've achieved that, you can begin to exceed their expectation.
The book really highlights that its the exceeding of expectations every time that creates a Raving Fan. That's true, and I would think that the pinnacle of success, but the whole point is, once you've re-evaluated your focus on your customer, you're on the winning path.
Again, great little read that shows you it doesn't have to cost you cash to make money.