Or a page settings/preferences dialog reminding you that saving your settings isn't going to work. Sure maybe the user "should know that", but not everyone is t

Or a page settings/preferences dialog reminding you that saving your settings isn't going to work. Sure maybe the user "should know that", but not everyone is totally in command of their own browser's settings. Or a game warning you that your progress will be lost. There must be tons of legit use cases.