Looking for a reasonable explanation as to why $_REQUEST exists

I have never had a use for this feature. To me it introduces another register_globals style atttack vector. I see no need why people need to combine post/get/etc variables into the same superglobal. I actually run unset($_REQUEST) on it at the top of my library to discourage its use. For third party products which use it I tell people to combine it themselves by using array_merge() - like $_REQUEST = array_merge($_POST, $_GET) etc... Anyway can someone here please give me a good reasoning why it should exist? It isn't as easily abused as register_globals but when people have a session variable they want to access and use $_REQUEST for it I could easily override it by using a GET param on the url (depending on how the order of globals get processed) Simply put, I see no reason why people would not want to clearly define where they are getting their input from. If for some reason there is some need to lazily code something I would still say to do something like: if(isset($_GET['foo'])) { $foo = $_GET['foo']; } elseif(isset($_POST['foo'])) { $foo = $_POST['foo']; } else { $foo = 'default value'; } ... or just do the array merge. But please someone maybe can justify this to me... I've been using superglobals before I really understood how important they were and then one day I see they introduced $_REQUEST and thought .. okay that seems stupid. I finally am deciding to see if anyone can give me a reason as to why this is useful and not just a lazy coding practice that can lead to security risks. You don't really know if your data is coming from GET, from POST, a SESSION variable, etc... I'd love to see a good discussion going on this. I might have overlooked something important.