From what I gathered it helps in scripts for sure. I replaced GondorAragorn with GondorStrider (ChildObject of GondorAragorn) in the campaign.
EquivalentTo = GondorAragorn is in its code. In the maps GondorStrider acts as GondorAragorn when scripts fire.
That was helpfull since the worldbuilder has rather bad habit of not cooperating.
(Made me given up modding for years becouse of the worldbuilder, now I managed to get it work again with some work arounds.)
Hope that helps, I didn't do more experiments with it.