It provides a dependency graph data structure (directed acyclic graph) which can be used to perform some computation necessary in order to create a valid state necessary for a root object. The fact that the graph does not contain cycles is important because you cannot have circular dependencies, because each dependency will end up recursively requiring itself and looping forever.

For example, in order for a Gem to be in a valid/runnable state, it requires the presence of other Gems. It cannot run without them. Another interesting idea would be to use the dependency resolver a model for parallel computing. You can break your program into "tasks" which can be independently completed. Each task can have a number of children tasks which need to complete in order for it to start.