Very nice post.
These divisions in former Yugoslavia are often driven by such absurd claims that one has to wonder if they are genuine arguments that people have or are intentionally planted discord. People can be very stupid, so I won't rule out the first one, but neither will I rule out the second one.
I think that the situation is like this because of mixture of those factors you mentioned. Someone played a chess game over Yugoslavia and people were and still are stupid enough not to see this.