Ouch. I learned that this was a management anti-pattern when I was younger from fiction of all places. I loved reading Piers Anthony, and I think it was in his Apprentice Adept series, there was a series of tests that a person had to take to become a citizen, and some of them were competitive. Of course, at one point the main character made the mistake of giving pointers to a competitor, and the competitor only got better as a result when they played a duet. It blew my mind as a teenager when the main character won the competition because his opponent played better when the two of them played together. It was such a foreign concept to me, that someone could act as a sort of force multiplier, and also be rewarded for it. After that, I don't think I ever hesitated to help bring people up. Even in college when grading curves meant others doing better could only hurt me, I'd still often try to explain things to people before a test.

It's a shame how many people never learned this lesson. Or maybe it's just a testament to how many bad managers there are that these are common things people get passed over for. Though, truthfully, if I were a manager, I'm a little afraid that I'd still be susceptible to this bias as well.