That is a very good point. I never considered the effectiveness of drones in large groups.
However, when we reach the stage where we can have autonomous drones acting in concert, the state of warfare will likely be autonomous machine vs autonomous machine. In such an era, wars may last only days but I wonder what the consequences will be for humans!
Wars are won by economics. So which country produces the most, coupled with how efficent they are in destroying the enemies infrastructure.
So you can actually calculate average cost to kill an enemy soldier / civilian. For things like bombing of factories you can calculate amount spent for each bombing raid versus the amount of damage incurred.
The dollar value of each soldier and civilian can be calculated. Since civilans produce things you can calculate his dollar value.
So if a country has a large population, and an AK-47 costs $100. If USA has to spend $500,000 on bombs or ordinance to kill the one guy with the A-47, on the longterm this type of war can not be one. So with drones it comes into cost per drone versus guy with rifle.
A pilot and aircraft is more valuable then an infantryman with a rifle. The pilot requires a huge amount of training, so from an economic standpoint, he is worth a lot more then an infantryman.
Morally speaking all life is equal. Dollars and cents will, sadly this is not the case. A 12 year old kid has little value economically, brainwash the kid to strap some plastic explosive on himself, he rushes some military checkpoint, blows himself up and kills 4 soldiers. From an economic standpoint this is a victory.