I think you misunderstood the post your replied to. That poster was talking about employees that have been going above and beyond their current role and taking

I think you misunderstood the post your replied to. That poster was talking about employees that have been going above and beyond their current role and taking on many/most of the responsibilities that their "promoted to" role would entail. The promotion is just becomes a recognition of the increased capacity that they are currently taking on.