American soldiers took casualties wherever we faced the Japanese.
Having dual tracks across the South Pacific and Central Pacific axes was a valid strategy. It kept the Japanese off-balance and they had to divide their limited forces to both fronts, particularly in naval assets and increasingly scare merchant shipping. While there was competition for resources between MacArthur and Nimitz, American industry was able to adequately supply both drives.
We will see how this pays off next June when MacArthur lands forces on Biak at the northwest end of New Guinea, triggering the Japanese naval response in Operation KON. A few days later Nimitz lands Marines on Saipan, a far greater existential threat to the Japanese Empire. The Japanese have to hurriedly scrap Operation KON, and shift to A-Go, the plan to fight for the Marianas. The IJN carrier fleet and aviation is gutted at the Battle of the Philippine Sea, while MacArthur gets a pass to seize land within B-24 range of the Central Philippines.
Yep. Considering how such a large quantity of Japanese raw materials passed through the South China Sea, retaking the Philippines would provide a base of operations from which the vital Japanese supply route could be strangled thereby greatly facilitating an eventual invasion of Japan.