I had a quick read through the perldoc man page for it and was thinking similar things. My thoughts at the time were "I'll have to come back and have a thorough read through this because I'm not seeing a great use of it right now".
As TomDLux alluded to above, the only real point is to simulate perl "builtins". For example a grep replacement would look like sub map2(&@) (as I recall) and let you do stuff like map2 { foo bar } @baz