Comment by KyleGospo

Fedora actually defaults to BTRFS, in the case of SteamOS the system is BTRFS out of the box, and only home and the SD card are ext4.

Main benefits are compression, and increased read speeds from compressed drives, especially from the MicroSD.

BTRFS de-duplication also solves the issue of wine prefixes with similar dependencies taking up more space than needed.