You will never win a war fighting proportionaly.
Nor fighting to win “hearts and minds”.
Yes, we have a name for those who respond proportionately in a war: losers.
I've posted my two Fundamental Rules of Winning a War many times on Free Republic (albeit in slightly different forms):
(1) The only way to win a war are (a) break the enemy's will to fight or (b) kill all of the enemy. No other way to win exists.
(2) You cannot care more for the enemy's warfighter and civilians than you care for your own warfighters and civilians.
Going to add a third Rule:
(3) You cannot allow outside forces to dictate your strategy or tactics.
"Proportional response" violates all three of my Rules.
Note: I am not formally trained. These are my own rules after studying a lot of world and military history for most of my life. That said, I think these Rules have held through all recorded history.