Not saying the war was sound policy by any means, but don’t care for the Soviet flavor of your take.
it’s a bit counterintuitive but let’s take the current capitalist vietnam.
One could make a very strong case, that Washington‘s involvement in the Vietnamese Civil War only delayed the outcome by 10 years. Therefore, if the Vietnamese Civil War ended 10 years earlier than it did, the transition to a capitalistic economy in Vietnam would have occurred 10 years earlier.
And we‘d likely have a ally instead of a hesitant trading partner.