There's a difference between preventing war and preventing a wider world war. Trade links persisting even when countries are opposed to each other contributes to a certain level of global order between the biggest powers.

If trade can persist in war then by definition trade will not prevent war

If

    A -> B
    not A -> B

then it cannot be said that

    B -> not A

And yet it has prevented a wider military confrontation over Taiwan, Kashmir, North Korea and continental Europe after WWII.

We do not and cannot so trivially assign a reason for the lasting peace since WWII. There are many theories in international relations that propose a cause, and none are currently accepted as being solely correct