That's if you consider only 3 target aoe girls and single target ones. But there're also 2 target aoe skills. That way it can happen that single target girl attack enemy hit by both 3 and 2 target aoe girls instead of go for that one who wasn't hit by later type of aoe skills. That's definitely not beneficial.
Kids doesn't care because all they want is to play. Thare're some people who like to think about stuffs.