It's the very definition of a dysfunctional organisation that continually promotes and keeps stupid people but gets rid of those with any talent.
Actually, a very famous author, Cyril Northcote Parkinson would disagree. You should track down his book Parkinson's Law. A highly abridge version
HERE, detailing precisely why you always want incompetent subordinate(s).
He has studied the history of boards and cabinets back to the 12 century and this short book is a real treat,In short, a study in organisational dysfunction although no longer politically correct, with the final chapter containing such quotes as:
To this the inscrutable Chinese replied, “Only coolie can become millionaire. Only coolie can look like coolie. Only velly lich man can afford to look lich.”