Even ants can move seeds around. Dispersal may or may not be associated with rewards to the disperser. Could give food, or could just stick to fur and drop later. Dispersal needs to be timed, if possible, when there aren't other species competing for dispersers. Survival may be better far away from the Mom.
Adults are better at getting the nutrients, the sunlight, and the water, than are small seedlings.
Adults may produce toxins to prevent anything, including the babies, from growing near them. Dispersal allows the population to find new, suitable niches. There may be other places to grow that are as good or better than where Mom is. Dispersal allows one species to suppress others - dispersal results in a greater area being occupied by the species. Dispersal promotes outbreeding which generally maintains the genetic strength of the species.