I remembered a Bungie interview where they talked about why you couldn't trade with friends or other Guardians in general.
If I recall correctly they said they wanted players to feel like they have achieved something when they got the loot. Like getting an exotic weapon from a certain Strike on a high difficulty (even as a drop with a low drop rate). Getting a weapon like that from someone else for free would destroy that sense of achievement.
Seeing people with zero kills in the Crucible getting Exotics makes me want to never play Destiny again.
Good work Bungie.
