This is my problem with design documents. If your stakeholders already have enough trust that they ask you to go build it without writing a doc, then what value

This is my problem with design documents. If your stakeholders already have enough trust that they ask you to go build it without writing a doc, then what value does writing a design doc have. Many will answer that it helps them think. But why do we need a formal process to think? Thinking is a valuable skill that should be practiced all the time.