US either has to build an Atlantic fleet or a Pacific fleet. Building an IC in Sinkiang then feeding it just slows US naval progression, which means delay in US’s ability to seriously project power in either east or west.
Generally Allied Asian ICs last a little while, delaying Japan’s advance, then Japan grabs them, then Japan takes advantage of the IC to gain a boost in momentum.
So what this balances out to is Japan gets a little bit less income at first, then gets a considerable boost in momentum from capturing then being able to use an industrial complex, but US’s advance is severely slowed.
The only way to have a hope of breaking this losing equation is a combination of careful planning and moderate to good dice results.
If you’re up against a good - not just decent - Axis player, you cannot just shove units towards Sinkiang/India and pop an IC on one or both, because the Axis will absolutely make you pay. If the Allies push protection to the ICs to slow Japan, Germany should gain in Africa and particularly Europe.