This would be a nightmare. For one people would just save lockouts on alts and grind the same boss until the item they wanted dropped.
For two, what do you do if everyone in the group has their weekly items but one guy, and he can’t even use the items that drop? He’d be the only one to loot them so he’d be stuck with items he can’t even use.
While your idea sounds good, basic analysis means you might as well just drop tokens instead of loot and let people get whatever item they want.