tbf the exact same could have been said about germans, the romans had a field day pitting the tribes against one another, and there was a religious war that depopulated like half of germany. if you had a strong political entity endure for like 2 generations, it would create a unifying identity. if yugoslavia hadn't turned communist and lasted for like one more generation, it would have probably fixed the balkans. problem is, no one outside would allow it.
Germany