I’m not sure I agree with this statement at all.
Promotion is never a touchy thing when you set clear expectations for a persons progression - one that is measurable and comparable to their peers.
The individuals then know, directly or indirectly, if they are on the right path, and which one of their peers is ahead or behind. The incentive there is for them to either up their game, or stay where they are.
The only fear there is that the system / process can be gamed; but one almost always never picks the lesser of the two qualified individuals - you risk loosing the more qualified individual and the team no longer has any faith in the “system” and they too will loose respect and move on.
Perhaps I may not have the experience you do, but it’s something I would never stand for - I would love to hear examples of when and such a scenario would play out though as it’s something I may encounter at some point in my career.