The point is it locks down a large part of the map and can blow up every single OKW truck ever if you put it in your base or spread them out.
if you place them outside your base sector then you should know they are weak to off map arty,if you have problems with off map arty then place them WITHIN the base sector(you cant target base sector with off map)
ALSO air suprimacy costs 325 munitions and has a long cooldown,it is also given to a faction that has early and mid game problems,its also a late game call in "arty"