Their "app store" is all the facebook app IDs that developers register to enable "login with facebook" and so on, in their own apps. Without an fb app, you cann

Their "app store" is all the facebook app IDs that developers register to enable "login with facebook" and so on, in their own apps. Without an fb app, you cannot access the facebook api or sdk. For example, pokemon go might offer "login with facebook" and that makes your in-game account gated by a working facebook app integration.