"A resource server is a server hosting the protected resources and capable of accepting and responding to protected resource requests." - OAuth2 specification.
Example 1: Let's say you've built a great web service that your customers subscribe to and you are looking to test your latest beta-service with select customers only. Those Organisations that you have invited to your new service can subscribe without having to resign up their users to this new service (self-managed subscriptions).Example 2: You have two customer accounts both using your Web Application but each customer has different IT policies. One requires that password refresh tokens are expired within 1hr (this client also requires it's user to use 2-factor authentication) and the other perferrs 24hrs (with no 2FA). No Problem! The each customer can manage this in the Organisation settings.
"A great benefit of organisation units is they have their own assigned identifier which allows you to filter response results without having to cater for this in your code".