Share a common message to multiple groups of people
Imagine you're a school district. Imagine your school district has 15 schools each with their own digital signage system. Now imagine that the school district has a section of those screens dedicated to content that they want / need to share to all the schools. 1 message, multiple locations. You have now communicated to all the schools in your district with a single message.
Create a community
With everyone on the same page you have automatically created a community of people that feel connected and informed all at the same time.