What i find the most interesting is the zeroconf option [0].

For example you can set up your spotifyd daemon on a raspberry and have it always connected to speakers.

Now when someone is in your local network they can choose your spotifyd daemon and play spotify over the speakers without connecting to the speakers directly via bluetooth etc.

[0] https://spotifyd.github.io/spotifyd/config/File.html (after the configuration file example)