Stakeholder management
Macbeth has one relationship that matters more than all the others, and he manages it by removing the man from the org chart. What is striking is how fluent he is in the language of loyalty right up until the moment he abandons it.
Before the murder, Macbeth gives Duncan a speech about obligation so polished it could be pinned above a desk. Duncan has just thanked him for his service. This is the reply.
Read it as a statement about work and it is close to perfect. The duty pays itself. You do not perform loyalty for reward, because the doing is the reward, and the obligation runs to the office rather than to the person holding it. Anyone would sign that. Macbeth means roughly none of it, and he is standing in front of the man he will kill within two scenes.
This is why the play is more useful than a case study. It is not a story about a man who lacked the right values. He can articulate them better than almost anyone else on stage. He simply had a stronger competing interest, and the vocabulary turned out to be free.
What real loyalty sounds like
Shakespeare gives you a control group. Banquo is under the same prophecy and the same temptation, and he says something that sounds superficially similar and is doing something completely different.
Banquo is open to advancement. He says so. What he will not do is trade his allegiance for it, and he sets that condition out loud and in advance, before anyone asks him to. That is the difference. Macbeth describes his duty in the abstract. Banquo names his price and puts a floor under it.
He says this to Macbeth, after the murder, not knowing. It is the same register Macbeth used on Duncan, which is the joke and also the tragedy. Banquo is killed within the hour. In this play the people who mean the loyalty speech are the ones it gets used against.
The part that shows up on the balance sheet
The consequence arrives four acts later, and it is not moral, it is operational. Angus is describing the state of Macbeth's forces.
Those he commands move only in command, nothing in love. Compliance without commitment. People still do what the org chart says and not one thing more, which is the exact failure mode every leader claims to fear and very few can measure until it is too late to fix. Macbeth got the promotion. What he lost was the discretionary effort of everyone below him, and the play is clear that the second thing was worth more.
The robe image is the sharpest part. The title fits badly not because he is small but because he took it in a way that made it unwearable. Authority he cannot fill, held by a man who can no longer command anything but obedience.