The people who design and build it understand the entire picture and can see the value (hopefully).
It can be very hard from the position of totally understanding a system, to put yourself in the shoes of someone encountering it for the first time, and it can be hard to see what they see when they first use it, and it can be hard to empathise with their journey through learning the software application that you have built.
This is an incredibly valuable article because it helps people who have built systems to put themselves in the shoes of their users - that is not an intuitive skill.