So what's the point of having alliances if those with the resources to spare (high prestige) cannot send them to those who need them ?
What happens when I send 100k troops to reinforce someone with low prestige and they need to stay there for any length of time?
Is the poor sap supposed to feed them somehow, because if I try to send food it will get taken by the system ?

For every action there is an equal and opposite reaction.