It would continually return the same value if you used a literal like Machine instead of $Machine.

It is very rare that a programmer would hardcode hash values like that. There are uses for it (mainly learning about hashes), but typically its done by reading data from another source to populate a hash for a (sometimes predefined) set of keys.

Running the command: perldoc perldata from your command_line/terminal should help you get more acquainted with hashes. Also just write some test hash scripts to learn more about the behavior of hashes. You'll always learn more by writing test scripts, and experiencing the behavior first hand.