This privilege is not biblical.
Neither is it supported is any JW teaching or publication.
The Catholic Church invented it, and its primary use is.... drum roll please...
TO GRANT ABSOLUTION.
Do Jehovah’s Witness elders, who seek the same invented privilege, also grant absolution?
If a JW elder hears “a sacred confession” then he must also grant absolution, absolving the sinner of his crimes.... er... sin.