Your "floodfill" approach has one disadvantage.
you have to store at least one value for each node.
Even for the shortest path you need a big graph ( who knows if there is a very high wall between the target or not )
And the more targets you have the more memory it consumes.

For Zombie games it would work out fine thousand of zombies are moving to the target
But for a RTS where are diffrent groups moving to diffrent targetsthe cost are much higher

Can you give some examples where your approach is implemented?


muffel