I never hear Gnome users crying about Valve heavily supporting KDE, so why are you angry about this?
This does not happen because Gnome is the most supported desktop environment out there, they have Red Hat, Google, Canonical, OpenSuse even Microsoft donated to Gnome. Don’t get me wrong some of this company do support kde too, but Gnome get treated in a different way because it’s the default de for most of the distros out there.