How could this possibly hurt the developers ?
If anything it would make players stay playing the game far longer because they are actually getting somewhere.
Ive been playing 4 months now and still cant max ascend a 5* hero because I still need heaps of items. And im getting very frustrated and its making me almost to want to quit this game.
I think if you could trade items with Alliance members it would make playes stay at the game longer and they have more chance spending money on gems in the long run. So i dont get this move by the devs to not allow to trade items.