Right, my youngest turned 13 and didn't even create a FB account until we told him too. He'd already been busy on Instagram and Twitter, but not so much on Snapchat yet.
Honest question: why would you tell your son to create an FB account?
One guess is to be able to have some intel and insight into what is going on in the kids life as well as their friends and who they interact with. Not sure if this is the parent comments reason but I can see it having some value for that reason.