How can it not? The players won't go to places the DM doesn't put in front of them. They would have no reason to travel to place X unless the DM provides place X. And, specfically within a level based system like D&D, many areas are more or less walled off by level. Yes, sure, you can wander into the red dragon's lair, but, since that's suicidal for 1st level characters, either that red dragon's lair will be in a location that the PC's can't reach due to lack of resources, or they will be strongly warned off by the DM through the use of NPC's.