SteamOS Used to Run GNOME: 6 Reasons Why KDE Plasma Makes Sense
The version of SteamOS that first came with the Steam Deck wasn't Valve's first attempt at making a Linux distro. It was actually version 3.
Before then, SteamOS used the GNOME desktop environment. But for the Steam Deck, Valve chose KDE Plasma instead.
GNOME is a more popular and arguably more mobile-oriented Linux interface. So why go with Plasma instead? We can't speak for Valve, but here are several good reasons.