Earlier quoted context omitted.
Well, one assumption didn't hold: that in a more economically connected world war would be a thing of the past.
Didn't we work this one out after WW1?
The idea was that if we don't want to engage them in a military way in a direct confrontation that by trading so much with each other that our economies would suffer substantially from either one breaking off that we would avoid doing so. The economical version of 'MAD'. That turns out to have been a mistake. What happened between WWI and WWII is not really representative in comparison.