> In short, we over-reward those at the top and dismiss the rest.
This is standard tournament theory: big rewards at the top to provide a strong incentives for excellence. Look at the prize structure in sporting events and at the three-medal rewards at the Olympics. Paradoxically the decline in quantity and quality typically seen after tenure suggests that it works in academic circles: post-docs and assistant professors are doing outstanding work because that's what it takes to "win".