If I'm not mistaken, that is still used in some parts of the pre-Home Sharing remote Library and remote playback functionality in iTunes (pre-Music.. man, that'

If I'm not mistaken, that is still used in some parts of the pre-Home Sharing remote Library and remote playback functionality in iTunes (pre-Music.. man, that's a lot of prerequisites). Remote events even worked across AppleTalk and TCP/IP, across macOS and Mac OS Classic, so you could make use of some of the features between computers on different networks, with 10+ years difference in software, and it would still 'magically' work. After RAOP and mDNS etc. the event system was less used and most of the newer features are implemented as classic client-server applications. But it still exists, and still works. Apple Events are even advertised over Bonjour!