Someone is interested in wargames because someone is interested in history.
The play of wargames and the study of written material go hand in hand. Quite normally, the interest in one begets an increasing interest in the other. The gamer is just as likely to pick up a game without really knowing anything about the historical situation and, using the experience with the game, read more and study more of the subject. The general surveys are quite important as they give a shape to one's researches. The specific sources are needed when one gets down to a particular game.