In addition to surfacing match rates, you can also use Addressable Audiences as a troubleshooting tool.
For example, let's say you send a segment to a destination and that destination shows low reporting numbers. Checking the Addressable Audience results will show you if this is a technical problem or just a case of low match rates. A low match rate shows your destination isn't all that great for your selected segments. However, a difference in the total addressable audience numbers between Audience Manager and the destination indicates an integration, synchronization, or other technical problem. In these cases, contact your account manager.