I'm afraid you have me confused with another commenter regarding the 'first-class support' issue.
If "platform" means "app development platform" and that means "full-featured toolkit for the development of GUI applications that run in an integrated environment", then I would agree both that Gnome and KDE fit that bill and that they have limited language support (in my experience the only language worth using with those toolkits other than the respective C and C++ is Python).
If "platform" means "app development platform" and that means "full-featured toolkit for the development of GUI applications that run in an integrated environment", then I would agree both that Gnome and KDE fit that bill and that they have limited language support (in my experience the only language worth using with those toolkits other than the respective C and C++ is Python).