What you're saying is true, but not simple. Suppose I'm providing a shoe-shine service. I understand my customers well and make every improvement I can think of, but still don't generate excitement. How do I tell if (1) the next improvement will lead to the tipping point or (2) no improvement will generate excitement until I target a different set of people more likely to get excited about shoe shining or (3) Nobody else is as excited about shoe shines as I am, and to generate excitement I need to take my service in a different direction? There are three possible paths. Which one leads to making something great?
(1) is the closest to the right path, though it's not phrased as one. And in fact you never do know when you'll hit the tipping point. So you have to work fast.
But your existing users are the place to start. There must be something they like about whatever you have, or you wouldn't be there. So you just have to learn to understand them well enough to turn that like into love. In the process you may appeal to a broader set of users, and as you iterate the "typical" user you focus on can move.
