ledarsi wrote:

The point is the intrinsic issues with calculating concessions this way.

If you and your opponent had a massive global war that left a continent in ruins, and the most you can ever possibly demand is the maximum difference in war score (100 - 0 = 100) then your massive epic conflict boils down to a single city changing hands in the end.

Whereas if you get to 100 war support and then kick the crap out of a border province and its defenders, dropping the enemy's war support to zero, same result.

Or the most pernicious case- there is a war where almost nothing happens. But then eventually one side's war score ticks down, and then actual concessions? Instead of just status quo peace because nothing happened?

War Score and War Support need to be two separate numbers. War Support represents your side's willingness to keep fighting, and nothing else. When one side runs out, it means they cannot fight any longer and must surrender unconditionally. 

War Score represents your accomplishments and damage inflicted during the war, and is the primary basis for concessions. War Support is used to determine when one side must surrender, and War Score is used to cede concessions when that occurs. The attacker should win battles and capture territories, get War Score, and use that war score to force the enemy to cede the captured territories.

It would also be a good idea to add the mechanic of a negotiated or conditional surrender, which could be done before your war support actually reaches zero. This would basically be the same screen as the forced surrender, but where the two sides must agree.

On point. Nothing more I can really add, you've said everything really.