Customers need to understand the product and the value a product brings them. Internal teammates need to understand the product so they can support, market, or sell it.  
In some cases, part of a product manager’s unwritten responsibility is to also champion the product management function across the organization. 

Conveying information and knowledge is a valuable skills for folks in product management.  In this episode, Andrea Saez, senior product marketing manager at Product School discusses how to effectively educate others on your products.