2FA is a basically a 2nd passwords or phrase or string or characters being used to authenticate you on a network or place that needs security, because there are a ton of people who are trying to get into your account and others.
While 2FA is good security, its also something that people can and do forget unless they are ver very careful backing up their passwords and codes and character strings. Once forgotten, that account is finished in places like Apple. They have no means to retrieve your information ever. Not tomention the staff are not priviliedged to help you recover that information in most cases. Apple is a kind of fort knox these days and many layers of management do not have access to their own resources, never mind something as deep as 2FA - 2 Factor Authentication.
2FA has been used in Bitcoin for years .. its been a long time standard in the virtual currency markets .. I wonder why its taken so long for apple to get on board. Maybe they are just not organized enough.. what ever the reason - its a 2 edged sword with apple .. 2FA so if you initiate it .. make sure the 1st thing you do is PRINT OUT all your passwords and secret codes and photocopy it 3 times then put them away.
Does this sound extreme ? Its necessary trust me .. I have lost 2 accounts with apple .. because they could not recover them even with a recovery backup device autheniticating you, its not enough. Any place that uses 2FA will have similiar rules. But you are beter off dealing with competant System admins, they are your best friend.
2FA is good, bad and permanent!