Seems to me that was Napoleon's prerogative as Emperor. I don't see him deliberately impoverishing his vassal states or allies. Your thesis is based on your incorrect assumption that all the French did was loot and that was their supply system which you have stated repeatedly. Again, it is an incorrect assumption. For a start, I would suggest that you read the Logistics chapter in Swords on how the Grande Armee's logistic system was developed, organized, and ran.

Sincerely,
Kevin