Yesterday I explained that one of the benefits of rotating the Lead position was to give everyone a chance at leadership to see who is good at it to avoid having permanent Leads that are not suited for the role.
The problem is that in many organisations, promotion to a management or leadership position is the only way to reward an employee regardless of their ability as a manager or a leader. So those who aren't good at leading (and they usually know it) will still ask for a promotion; or well meaning executives may promote someone who didn't even ask, just to show they value them and their work.
Either way, promoting your best expert to a Lead position means they will never contribute their expertise to the project again because all their time will be spent leading the team. That very same expertise that made them so valuable in the first place is now wasted.
Worse, they are now in a position to manage others, something they have no experience or aptitude for. They will hate their job, become disengaged and leave - but not before their poor leadership skills cause their reports to also become disengaged and leave. You lost your best expert and a good team.
Instead, you could offer two career paths: expertise and management paths, both sharing the same revenue ladder so there is no reason to opt for one rather than the other except skill. It gives both future managers and future experts the same chance at growing while staying in your organisation, adding value to your products.
Creating two career paths doubles the number of excellent employees that can be promoted and it gives a chance at promotion even to those who aren't interested in (or good at) becoming leaders or managers.