Just like with Video distribution it allows you to de-clutter your space from Hi-fi equipment and install all your amplifiers and streaming devices in a centralised location.
Audio sources can then be streamed in different rooms around the house. You could be listening to Spotify in the shower while another person could be listening to the radio in the garden. The speakers can also be used for notifications on event alerting you when someone is at the gate or when a door has been left open, the possibilities are endless or as we like to say infinite.