I blame King Louis 15th. He dropped the ball after France's best king. The financial problems associated with his reign set the stage for the French Revolution. And most importantly, he annexed Corsica. From which a young Artillery officer would rise to terrorize Europe.

Then after that guy, whose name nobody remembers, was properly exiled the Continental Monarchies agreed on a balance of power system. This was largely influenced by the fact that so many of them were actually related via the Habsburg family. And more than a few didn't have any other family line... Look there's a reason for the "Habsburg Jaw" okay?

Which brings us to the entire reason Serbia was stuck with the Habsburgs ruling part of what they thought should be Serbia. It was part of the Balance of Power idea from that period. The idea that was put in place to prevent any more unnamed Corsicans from conquering large swaths of Europe.