It became necessary when Roon Labs added AirPlay 2 support here:
The Muso v1 has support for AirPlay 1 but not 2. There should be an automatic fallback for older devices, which seems to work for many but not all AirPlay 1 devices. So Roon added the Compatibility Mode for those, but for some reason it’s not enough for the Muso 1.
According to Roon Labs support in some other support topic about this issue, they intend to add a better solution in a future update, but for now it needs the Home app workaround.