Wireframes are an easy way to communicate the functionality you are looking for, and you don't need much experience to create them. It's a great idea for product managers to share wireframes with designers, developers, and other teams involved in the process. Together you can identify possible issues and suggest solutions.

Wireframes also work great in Agile environments. For example, a product manager can use wireframes to plan what each team should tackle for each product iteration. For example, tackle the Main page first, then add a catalogue, etc.

When working in iterative chunks, you start getting feedback early in the process. This allows you to refine the design and development process as you go, saving time and money.