In Animal Farm, how do the animals that do less work support Orwell's criticism of Communism?

One common
criticism of Marxism-based ideologies, such as Socialism and Communism, is that those who work
will ultimately devote all their time to supporting those who do not work. This includes the
ruling class that always develops despite Marxism attempting to remove any sort of class system,
and people who understand that they will receive communal support no matter what and move from
working to gaming the system.

Somehow...