Smaller realms only have 2 options in war against a bigger realm.
1) Battle with the bigger realm's army and get crushed.
2) Fortify their capital and get everyone to remain there in hopes of outlasting the war.
If the looting reform is passed through, it opens up a myriad of options for smaller realms to take.
By being able to Loot the regions of bigger realms, it may ensure all form of fuel(Gold) is stopped from entering the war machine thus it becomes a cat and mice game whereas the bigger realm tries to catch the smaller realm while the smaller realm flee.
Slowly the war comes to a close as the larger realm is unable to upkeep it's army due to lack of gold. Lots of things can happen during this time, perhaps smaller realm is able to stand against a diminished army.
That's how it plays out in my mind, of course it may not go that way but it is a possibility.
Hic Sunt Leones,