The metrics which determine if someone gets promoted. Those decisions are being made by some group, presumably with guidelines. If the process for getting promoted is "this group does whatever they feel like" that company is a disaster and you need to get out.
Thus, there are rules, and they are written down. If they're not visible to normal employees, they guess the rules based on who they see get promoted (cargo cult) while the committee uses the true metrics.
It's not like becoming a manager is a secret cult where you're dropped in and you suddenly have carte blanche to do anything. At established companies there are rules and procedures, and while you will likely have access to more information than individual contributors, you won't just be promoting whoever you feel like without having to go through others.
Thus, there are rules, and they are written down. If they're not visible to normal employees, they guess the rules based on who they see get promoted (cargo cult) while the committee uses the true metrics.
It's not like becoming a manager is a secret cult where you're dropped in and you suddenly have carte blanche to do anything. At established companies there are rules and procedures, and while you will likely have access to more information than individual contributors, you won't just be promoting whoever you feel like without having to go through others.