> Theoretically we don't actually need proof of age. Websites need to know when the user is attempting to create an account or log in from a child-locked device. Parents need to make sure their kids only have child-locked devices. Vendors need to make sure they don't sell unlocked devices to kids.

Given how current parental controls work, kids are not getting access if their device is under parental control (the default for open web access is off). So Facebook still won't see any child-locked devices, even before this ruling. My guess is that this ruling applies to parents who aren't making sure their kids get access only via child locked devices.