What evidence do you have to make this claim? A simple thought experiment proves the counter. Let's say there is a population on one island, and another population on another island, and these populations have no way of reaching each other or even knowing of each others existence. These not-connected populations are guaranteed not to go to war. However, give one of them the means of reaching the other population, and most assuredly the chance of war has gone up not down.
If you like ad absurdum arguments: if you connect the countries together so much, they eventually decide to become one country and the chance of war goes down, not up (excluding civil war)
Austria, World War II. Some people saw annexation, others saw reunification, others still saw a bunch of cowards surrendering without firing a single shot.
With all of these things, context matters. If memory serves, Austria being an independent state was one of the terms of the Treaty of Versailles, so if that had been the last act instead of the opening chapter, there still would have been hell to pay. Perhaps not on a par with Caesar crossing the Rubicon, but definitely starting something that requires a resolution.
I don't think they like ad absurdum arguments. But without systematic evidence, there is not way to determine if if such an argument is actually any less valid then the initial claim.
not absolute 0 % chance of war