I think that with some basic knowledge it's easy to check someone's identity on the Internet
Imagine for a moment that there's no Internet at all and I told you I'm someone else, how would you check if it's the truth?
Most of the controversy about the Internet is not about people having a secret identity, it's the opposite
You make an extremely valid point! The internet is probably the easiest way they check an identity. This author particularly made this photo in regards to all of the children that talk to people who really aren't who they say they are. I think that is a problem meant for the parents to sort out and monitor but it does happen daily.