Why is this important if you want to make improvements?

It’s a starting point. It clarifies the current processes and describes how things currently work. Writing out procedures, drawing diagrams, discussing them so that they are clearly understood is a key step.

Communicating what is currently happening to each other, to new team members or outsiders becomes easier.

It may be that all is fine, nothing needs to be changed, the way things are, works.

It may be that you begin to see that improvements can be made.