Perhaps it was just a bad example, but your minority use case rivals my own, which is that I do not save credentials on my Facebook app. Again though, if app_x

Perhaps it was just a bad example, but your minority use case rivals my own, which is that I do not save credentials on my Facebook app. Again though, if app_x implements login-less transactions, perhaps using phone number or phone SSID, or Google oAuth, then they're ahead of the Facebook app, login-wise.