I didn't claim anything such as this and I'm having trouble understanding what you are responding to in my post.
A utility function is just a value of utility received at different quantities and costs. They are just basic models for helping to simplify our understanding the world. There's no need to begin comparing expertise with utility functions. The author is talking about the utility he receives at the margin of one additional widget in his decision making process, and what that this type of scenario (when a commonly cheap item can, in our decision making process, can have a high marginal utility--ie quantity is only 1 and 1 is necessary for a finished product) means to us in our human experience.