Possession of the Philippines denies Japan imports from the Dutch East Indies which is why they went to war in the first place.
The Japanese invaded in 41' to deny the US Clark Field on Luzon and the Navy yard at Cavite.
The last Japanese tanker from the Indies limped into Japan in March 45'.
It had been bombed by B-24's from the Philippines and had to jettison much of it's cargo to make it.
We didn’t need the Philippines for that. Once we took Iwo and Okinawa, Japan was finished. All we needed to do was get within bomber range and we did that from Mariana Islands