You could not pick up anything at all in third person: no stone, no ore, no berry would go in your pack, and the prompt would not even appear. The game measured whether something was within arm’s reach from the camera, which in third person sits nearly three meters behind you, so a stone at your feet was out of reach by a meter. It now measures from your own head and aims with your crosshair, which is the same thing in first person and the right thing in both.
Throwing in third person works for the same reason. The stone used to start from the camera behind your shoulder and the throw was refused for starting too far from you; it now starts from the hand the stone is drawn in, so the rock leaves the hand you can see.
