lol, it seems the trend for everything nowadays
"We need you to integrate your Facebook account with our website"
"Can we have your mobile phone number so we can send you text advertisements?"
"Link your Google+ account with your Youtube!"
etc...
Very silly, in earlier days if someone had your email, they had everything, which is still true, however genius' today decide to make it easier for others to grab a hold of your entire online life by linking now everything together. Somebody has your Youtube? Maybe they have your Google+ or your Gmail? Or if they have your Google+, maybe now they have your Facebook? Now if they have your Facebook maybe they have your email and your mobile, and through this chain of events soon enough perhaps maybe now they have your bank account credentials?
Very very silly... I've tried hard to keep everything separate for years, and now they seem it's better for convenience matters to link everything together for you?
So again, this security with your cellphone? Exactly what does it do, other than give that person who maybe has hacked your account your mobile, giving them greater access to even more things?
I have a friend who gets paid to hack Bell systems for security testing, and I know very well how most of this stuff works because of my curiosity with everything involving computers. (You name it, Graphics, Video editing, Music, Programming....)