Choaza flattened the Pain that absorbs all attack.
She could have done the same. But she choose to use her chakra in a way to save a bunch of useless fodder. Rather then focus it on the kick ass fighters.

I guess I am still bitter that the so called healing/chakra transfer didnt get to Kakashi in time. IF she had provided Kakashi with all the chakra he needed. Kakashi would have pwned the Pains with his mangakyo and then some.