This is definitely a potential risk. However, you have this risk with small teams (less than 10 developers) even without hero roles. The smaller the number of d

This is definitely a potential risk. However, you have this risk with small teams (less than 10 developers) even without hero roles. The smaller the number of developers relative to the complexity of the product, the higher the probability of a single point of failure. However, you can reduce the risk through good documentation, good engineering practices and so on. As long as you are aware that the team is partly made up of heroes, you can prepare accordingly. So as a manager, I can try to ensure that a few heroes keep productivity high while making sure that the rest of the team understands the basics of the system through things like code review and the like. In the worst case, a teammate can then at least get up to speed quickly.