Solution for loot leeching is easy.

Combat chests should contain loot only those who participated can roll on.

Gatherer chest loot should go to the person who found it.

It's unfair for gatherers to be able to loot items they didn't help with getting, and for items from gatherer chests to go to people who didn't do anything to get them either.

It's really that simple. Why it's not done that way is baffling to me.