As a long time GNOME user, I am so glad they decided to go with KDE. GNOME has a trajectory going away from the desktop. KDE Plasma has all the small little tools and utilities you expect in a full desktop environment. I switched to KDE plasma on the announcement of GNOME 40.
To be fair to GNOME 40, they are not so much moving away from the desktop as such, but more towards convergence also with tablets, and mobile, while remaining desktop-level competent even on those smaller devices. I think Valve chose KDE more because it’s less resource-heavy.
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE’s software runs on GNU/Linux, BSD and other operating systems, including Windows.