It doesn't seem that it's exactly 'discouraged'...
Our Kingdom Ministry, April 2008, page 8:
Some funeral homes have appreciated having some appropriate literature on hand for grieving families. At times, funeral notices appearing in the newspaper have opened the way for writing a brief comforting letter to bereaved family members.Even worse... Our Kingdom Ministry, October 1994, page 7:
You may wish to visit local funeral homes in your territory to see if they would like to have copies on hand to comfort bereaved families. Or you might tactfully approach grieving ones in cemeteries on occasions when they return to visit the grave of a loved one.