SteamOS is based on Arch but doesn’t follow the same release cadence, as well as using an immutable base OS and an A/B partition layout (much like Android) allowing for rollbacks. So the problems that an Arch user may run into are less likely with SteamOS, because it has some extra protections and testing that is done before it arrives on the user’s device (particularly with the stable channel).
And gaming distributions often prefer a rolling release setup, because gaming benefits from very recent kernel and GPU related packages (that aren’t always fully compatible with older/stable distributions), particularly with AMD hardware.