Here is a challenge for you: go online and search what skills are sought by employers and their recruiters. You will find the various articles are consistent and skills that are in demand include communication, leadership, and the ability to motivate. Now consider coach training: during coaching certification there is an emphasis on communication and motivation plus ultimately leadership is about asking questions, considering options, developing strategies, implementing plans, and empowering others. What does this all mean? Coaching certification makes sense for job seekers and leaders alike.
Push that even further: coaching is essentially a workplace competency. Ultimately we recognize that the old style of leadership, wherein the leader told everyone what to do and how to do it, is at best ineffective. Leadership that is effective is a coaching style. How does that work? A coaching style of leadership means exploring opportunities, challenges, and outcome possibilities. Leaders using a coaching style ask questions and listen, plus they empower the people doing the work to determine their process. Coaching is positive, proactive, solution focused, engaging, and motivating.
Because a coaching style of leadership is so clearly effective, and more so than other styles of leadership, it makes sense that when looking for a leadership role or ways to advance careers, coaching is an essential workplace competency.