A professional writer needs to know what information is valuable to different people in the workplace. A PW needs to know at what level his or her co-workers are communicating. Are they using very technical terms that would need explaining to someone not in their field, but could be used in inner office memos without explanation?
A PW needs to know the limits on length for certain documents. The writer may make things more difficult than they need to be by creating a document that is too verbose, and wastes a lot of time, or on the other side, write a document that is too concise, and doesn't provide the right information. A PW needs to recognize which departments need his help, so that messages get passed to the right people, at the right time. A PW needs to understand that his or her job is to help create purposeful information, not to do the work of everyone around the office. A PW is not a secretary.
A PW needs to facilitate the meeting of ends by the different interests of all the different sections in the workplace, by helping them communicate on the same level.
A PW should be like an old fashioned telephone operator, listening to the needs of the caller, and patching them through the right channels, to get to them to the right place.