This is very good but.....this doctrine went out of the window in the Pacific during the last year of the Pacific War when the Japanese started using Kamikaze Suicidal Tactics.One of the classic "get your measures of effect" right was AA defence of merchantmen on the Malta run in 1941-2.
With "not enough" AA guns to go around, one argument was to concentrate them on "flak ships" where a battery of guns, with better fire control and better-trained crews, would be significantly more lethal to attacking aircraft than scattered weapons fired in local control by scared DEMS gunners could be.
This was winning the day - shooting down enemy bombers is good, right?.
Until someone checked the statistics to date, and noted that 25% of unarmed ships attacked by aircraft were sunk or badly damaged: while armed ships (even if just a couple of 3" AA guns and some Lewis or Hotchkiss machine-guns) only had a 10% rate of "lost/badly damaged".
"Shooting back" - even if not very effective at bringing down the bombers - still made a big difference to a ship's survival and their ability to reach their destination; was the mission "shoot down a few Luftwaffe/Regia Aeronautica bombers" or was it "get cargo to Valetta"?
Air defence against manned aircraft - like ASW - is not about destroying the enemy (it's a bonus if you can do that, but it's not the point). The enemy is trying to stop you doing something (evacuating troops, transporting cargo, invading them...) - if you achieve that despite their efforts, you win even if every one of their bombers or U-boats returns home undamaged. If they slaughter the convoy, it's no consolation to point out that you did shoot down half-a-dozen aircraft while they did it...
The only real defence against them was to shoot them down/destroy them completely, driving them off was NOT an option.
This in turn brings us back nicely to the argument about Armoured Vs Wooden Flight Decks fitted to Allied Aircraft Carriers......