You have raise a good point but I am not surprised by it. Although we are taught at school that the best workers should get the promotions, I personally even took an Engineering Ethics class on how most of these things should be dealt with. However, the teachings at school are very far from what actually happens. I personally have never seen something like that occurring, but I can imagine that at the end of the day, the person who gets the promotion is the boss’s best friend. So at the end of the day, the major objective is to keep the main boss happy. I think it is important to mention that the person who does a job in the best possible way always gets rewarded at the end of the day (somehow), maybe not by the same boss, but by another company who liked the way that employee performed.

Let me know what you think
Sincerely,
Roberto Pineda.