I can describe what I want in a sentence, and everyone nods. Then engineering builds it and it's nothing like what was in my head, because I never wrote down the parts I didn't think to say. Describing it is easy. Pinning it down so it gets built right is not.
More people experience this than they realize.
You can describe a feature, but specifying it so it's built right eludes you.
If this sounds familiar, the Library can help you find the bigger picture.