The rich get richer. I remember filling out school and early job applications. I was struck by how my list of awards and recognitions was kind of a sham—most of them were each a consequence of some earlier achievement, and so on. It felt like getting a check and being able to cash it more than once.
Achievement and power are runaway positive feedback loops which means we need damping forces to have any reasonable level of fairness where "fair" means reward is proportional to the effort.
The results and outcomes alluded to in each comment, mine and the one you're responding to, are consequences of essentially begging the question. It's that part where the flaw lies—because it leads, as in your comment, to justifying things as rational and fit even when they are not equitable.
Scientist A and Scientist B both produce results X and Y respectively that are exactly equally valuable to the world. However, Scientist A happens to already be well-known for other work. What we observe is that A will get more accolades for X than B gets for Y. Not because X is more valuable, but solely because people assume that since famous scientist A did X, it must be worth more.