I agree with the DID as being a rough blueprint to the customers input as @amd29 had stated. The example I disagree with because it does not compare to medical devices since their tends to be more regulations and scientific attributes associated with the field. The example is more for an interior designer then a engineer.
To answer more on the DSD it’s the engineers job to take what management gives them and to put it into the language of the engineer which is more technical and analytical. I find it challenging to filter what people want based off minimal exposure to the customer. That’s why I believe engineers should also speak with customers not just marketing.