Shortly before legendary management guru Peter Drucker's death in 2005, he made this bold declaration: Increasing the productivity of knowledge workers was "the most important contribution management needs to make in the 21st century."

What are "knowledge workers?" Drucker simply defined them this way:

Knowledge workers are people who know more about what they are doing than their boss does.

We've reached an era where the ever-increasing presence of knowledge workers, especially technologically savvy Millennials, is rendering top-down leadership structures virtually obsolete. This is a good thing.

Today's leaders are a different breed. This leads me to answer the question in the headline--the one thing great leaders never do? Assume they know more than the very people they lead.

Twenty-first-century leaders are servant leaders who recognize the power of shared status and shared decision-making. They don't pretend to be "the expert." They leverage the skills and education of their knowledge workers on the frontlines, and enable them to contribute great ideas that lead to great customer experience.

While today's leaders may not be the experts, they still play a critical role in helping their tribe achieve their goals. Here's how they lead today's highly skilled knowledge workers.

1. They lead by coaching and facilitating.

The "ask versus tell" approach is perfectly suited to leaders in the knowledge economy. They don't tell their knowledge workers what to do, but rather ask powerful questions that allow them to create their own solutions. This thought-process works well with smart workers who prefer to own the solutions to their own problems. The role of the leader is about empowerment--increasing his or her tribe's development and facilitating the learning process through a coaching approach.

2. They lead by developing their workers for the future.

With more global competition, today's leaders look to the future to help their workers gain the know-how that will keep their skills sharp and relevant, while helping the business be successful tomorrow.

3. They allow the freedom for workers to build professional networks.

Knowledge workers become loyal workers when given the freedom to form or pursue strong networks both inside and outside the organization. Professional networks add value as workers expand knowledge and bring back to the organization new skills for competitive advantage.

4. They lead by actively involving others.

Great leaders recognize that leadership is multi-directional. While it can come from the top down at critical times, the best scenario is allowing it to travel from peer to peer or from the bottom up, where the collective wisdom of knowledge workers helps solve real issues on the frontlines.

5. They lead by demonstrating their own competence.

Lastly, let's quickly erase any assumptions that leaders of knowledge workers are mere doormats. On the contrary, they exercise great influence by holding their own--demonstrating keen knowledge, insight, and expertise in both leadership and industry- or technology-specific business acumen. In the leadership sense, they will carry the vision forward, communicate the vision, and actively engage their tribe in pursuing the vision. This takes competence, and builds confidence in your tribe. And their confidence in you, the leader, will ultimately deliver excellence.