I absolutely despise these statements, that are perpetuated to the present day. I'm from near the Balkans, from Romania.
They depict the Balkan region as being some sort of backwards warmongers, which is not the case (yes, the region is not very developed but it's far from the poorest regions on this planet; also, yes, I know about the Yugoslav Wars, but that's a rather extreme scenario and even people in the region were appalled at what the Serbs did, especially).
Anyway, the reason I don't like it: it was foreign empires vying in the region that made the mess. Turks, Austrians, Russians, Brits, Italians, Germans, French, they're the ones that started the wars. There was no way the local conflicts would have ever become global conflicts. The locals just didn't have the desire or resources to escalate such a conflict. Instead these empires just used them as battering rams against the other empires.