So, poor performers can be identified if "they don't have enough roles" or "they're not a good fit for the company culture". What happens to them? I guess there are executives at a higher level that have the authority to fire these poor performers?

These "lead links" sound like managers with less authority to me.

If they are hoping for natural leaders to step forward then that seems how you become a manager in that company, you ask for it. Which, in some cases, is probably a better system than what many companies have in place that places people in roles they shouldn't be in.

The roles are still there, some of the requirements and responsibilities are shifted a bit, but they just removed the titles.