One popular aquarium fish is the Shark. The reason is that sharks adapt to their environment. If you catch a small shark and confine it, it will stay a size proportionate to the aquarium in which it lives. Sharks can be six inches long yet fully mature. But if you turn them loose in the ocean, they grow to their normal size.
The same is true of potential leaders. Some are put into organizations where growth is not encouraged and the confining environment ensures that they stay small and under-developed.
Leaders should create an environment conducive for growth.