Oh, oh, down they go for all the wrong reasons - Tom PettyNot everyone who has the potential to be a leader wants to step into a formal management role. Taking on the mantle of leadership has its rewards, but it also carries a variety of burdens. Some folks recognize this and some have learned it the hard way, and they may simply not want to assume the extra responsibility and stress. Hopefully, a mature organization can recognize that these folks can still make valuable contributions without requiring them to become leaders in a formal sense.
People can "lead" without having to be recognized with a title and formal authority. We see this most often with "thought leaders" -- those whose insights and observations ring true for many people who will, in turn, start to pay attention to the words of wisdom they hear from these folks. Many people around the world, for example, deeply appreciate - and follow - the insights of the Dalai Lama, even though they are not Tibetan or necessarily follow Buddhism. They don't follow him because of any formal authority - but simply because of the content of the thoughts that he shares.
Taking this a step further: for those who share insights, wisdom and perhaps constructive criticism of an organization, taking on a formal leadership role might actually have a negative impact on the contribution that these folks are making. Across my own career, I've had the opportunity to play various roles as inventor/architect, thought leader, as well as executive in charge of various organizations. In some organizations and cultures, the combination was accepted and beneficial. In some others, when I took on an executive title, I was clearly expected to curtail my former contributions. That works for some folks, but I learned a powerful lesson: if advancing in an organization means dropping those intellectual pursuits that I find personally rewarding, then either the role or the organization is not the right one for me.
Billy Joel once said, "If that's moving up then I'm...moving out". Formal leadership roles are not for everyone. We should each be able to contribute as best fits our personality and capabilities.