Everyone can be a leader.

Not true. Many executives don't have the self-knowledge or the authenticity necessary for leadership. And self-knowledge and authenticity are only part of the equation. Individuals must also want to be leaders, and many talented employees are not interested in shouldering that responsibility. Others prefer to devote more time to their private lives than to their work. After all, there is more to life than work, and more to work than being the boss.