Account security is a tough issue for a lot of people. It's a constant balancing act between having a stronger system to keep out would-be invaders while also making it convenient enough that users won't reject it. After Google began offering its own 2-step verification system, several other services adopted the same mechanism and opt-in model for people that wanted more than a single password protecting their personal data. This generally left users with Google's Authenticator app, which got the job done, but it lacked features and languished on an early Holo dark design.