Why be concerned with “modeling” behavior for employees?

Why be concerned with “modeling” behavior for employees?

 

https://www.worldcat.org/title/umikers-management-skills-for-the-new-health-care-supervisor/oclc/960494748/viewport

This is the book i am going by

2. Why be concerned with “modeling” behavior for employees? The supervisor is the boss—why not simply tell them what to do?  Chapter 6