[hinkley]

For several bosses, this scenario you describe has fallen under the concept of 'kill your heroes'.

Sometimes the person really is brilliant and you should do anything to keep them. But if it's because they're the only one who understands their code, then they are a liability.

[pdimitar]

Is it really so difficult to train other people in the code?

Or is the hero deliberately sabotaging such efforts to maintain scarcity, and thus their higher value?