Exactly, this is where the real problem was and thankfully it was fixed. An attacker could insert any variable in a script just by adding it to the URLs additio

Exactly, this is where the real problem was and thankfully it was fixed. An attacker could insert any variable in a script just by adding it to the URLs additionally the PHP configuration could change variable order the variables from different sources were given so a script essentially didn't know where it was getting the information from. On the other hand the super globals are just a utility making things easier for the developer, they don't directly make code insecure.