Why did the World Government destroy Ohara?

The World Government destroyed Ohara because its scholars knew about the existence of that kingdom. Shaka states that twenty-two years ago Ohara was destroyed with a Buster Call from the Navy because Ohara knew about that kingdom ch. 1066, p. 3. During the Void Century a highly advanced civilization existed and the history of the battle between that certain kingdom and the twenty kingdoms was erased ch. 1066, p. 3. The winners were the twenty kingdoms which founded the World Government known today and they erased its existence from history to make sure nobody carried that kingdom's ideology ch. 1066, p. 3. The researchers in Ohara made a theory from researching many important documents and the Government treated the theory as truth ch. 1066, p. 4. "I THINK THE REASON IT GOT DESTROYED WAS BECAUSE OHARA KNEW ABOUT THE EXISTENCE OF THAT 'KINGDOM'." ch. 1066, p. 3 "TO MAKE SURE THAT NOBODY CARRIED 'THAT KINGDOM'S' IDEOLOGY, THEY ERASED ITS EXISTENCE FROM HISTORY." ch. 1066, p. 3 "THE WINNERS WERE THE '20 KINGDOMS'. THEY FOUNDED THE 'WORLD GOVERNMENT' THAT THE WORLD KNOWS TODAY." ch. 1066, p. 3