Why don't purely functional languages use reference counting?

Question

In purely functional languages, data is immutable. With reference counting, creating a reference cycle requires changing already created data. It seems like purely functional la

Answer 1

Consider this allegory told about David Moon, an inventor of the Lisp Machine:

One day a student came to Moon and said: "I understand how to make a better garbage collector. We must keep a reference count of the pointers to each cons."

Moon patiently told the student the following story:

"One day a student came to Moon and said: 'I understand how to make a better garbage collector...