What would the incentive be for a mean, or even underperforming, worker to look at the pay of a top performer and do anything
other than argue for more pay for the same amount of work? The value a worker brings is not a completely tangible assessment, it has vague and qualitative components to it. Whereas, how much that worker is paid is a hard quantitative fact and is not debatable.
If you remove the ability of the manager to obfuscate where an employee's earnings stack up in the absolute rank, or how much additional pay is on the table, then the only thing to argue about is how much value the worker brings. The worker will always be able to claim that they deliver unmeasured value, or that their tangible contributions are not properly valued. Multiply this conversation out across 50% of your work force, and quickly the only rational thing to do, as a manager, is to bring down the top earner's pay to a level that will not generate complaints from the mean worker.
This is the aim of all collectivism frankly, to appease the mean producer at the expense of society ultimately.
If you don't believe this, explain please the chain of reasoning that would lead a lower paid worker to conclude their pay is fair and that they should not try to argue for more money.