The reason for this flawed system is that businesses use the wrong metrics to reward their workers. When looking to promote someone, higher-ups tend to pick their best employees, i.e the ones who are great at their current job, instead of trying to figure out which employee would be the best at the job they'd be promoted to. After all, just because you're the best rodeo clown on the circuit doesn't mean you're cut out to be Head Rodeo Clown and organize the Barrel Safety seminars.
Of course, the notion of your bosses always rising "to their level of incompetence" has been more of a universal intuition than a well-tested theory, but that has changed now. Researchers have published a study offering empirical evidence that the Peter Principle is true by examining hard data of sales teams and their managers from 214 different firms (because it's easy to determine competency in a field in which your entire worth is ruthlessly derived from how many dictionaries you can sell per minute). Data showed that when ranking each member in a sales team, the chances of them getting a promotion rose by a massive 15 percent per rank. However, when promoted, that same ranking comes with an incremental 7.5 percent decrease in productivity to all of the new manager's subordinates. So quite ironically, the better someone was at making sales, the worse they were at selling their employees on them being a good manager.
20th Century Fox