Why can't people invite or add friends without having to do it through Facebook? Not everyone has Facebook or wants to get it just to add friends. You should have that as an option for those who don't want Facebook. Thank you for your time!

It is true, it does not have to be necessary to add a stranger to Facebook, but if you should add acquaintances in the game, without the need to share personal information, such as mail or social networks, it would be protection for minors.