Just my opinion.
Old school D&D has the emphasis on the setting. Megadungeons, fantastic castles, Tombs of horror and Temples of evil - these were the things that players hurled themselves against to gain gold, glory and the satisfaction of saying "I survived."
Makes sense when you look at it from the aspect of a wargamer - wargames are about surviving the scenario. The scenario is all - players are merely units to perform orders and fight battles to see who will overcome the whole of the scenario. You might make history, you might rewrite history.