Valve chose KDE for SteamOS, including as the desktop mode on the Steam Deck, a device sold to be so user-friendly that it can compete with home consoles includ

Valve chose KDE for SteamOS, including as the desktop mode on the Steam Deck, a device sold to be so user-friendly that it can compete with home consoles including the Nintendo Switch. (Not saying that desktop mode itself is as foolproof as a console interface, just that it can't be a total usability disaster for people who bought a Steam Deck for gaming and not as a Linux desktop) Emphasis on chose KDE, not forked KDE. I agree with people who say that KDE has gone to great lengths to be customizable enough that you can mostly set it up the way you want without forks, extensions, or even registry editors. I can't speak to how difficult Valve found it to work with KDE, but it says a lot that they still chose it overall. It's not often we get such a clear positive signal from a company that invests so heavily in user experience.