Is a participant or an outside observer best suited to tell a particular story?
Someone who was directly involved in significant events or a major program may have the knowledge and the personal desire to see a story told. However, an outside historian may have a more impartial perspective. Historical writing is also very different from technical engineering or natural science writing. Thus, an outside historian or other social scientist, such as a political scientist or sociologist, presumably would be more experienced in nontechnical historical writing.