Face Pulls - Muscles worked?

Hi, my friend told me to ditch rear delt flys as they are made redundant by face pulls. He said that rear delt flys only hit rear delts and mid/lower traps whereas face pulls (done on lower cables like the seated row machine) hit all those muscles as well + upper traps and medial delts. Is there any truth to this? He tried explaining it but I still dont really understand how upper traps and medial delts are involved. Please help. Thanks! I didn't find the right solution from the Internet. References: https://forum.bodybuilding.com/showthread.php?t=175373541 Business Solution Video