The lesser extent of Nebuchadnezzar IV's rule compared to that of the preceding Nebuchadnezzar III probably accounts for why Darius thought it sufficient to send one of his generals instead of leading a campaign against the rebel himself.
The lesser extent of Nebuchadnezzar IV's reign compared to his predecessor, Nebuchadnezzar III, likely contributed to Darius' decision to send a general instead of personally leading an attack against the rebel.