Just because something like melee decays 100% doesn't mean
ma gets 100% of it.
My belief is that the formula they use is amount of ped in loot pool times a certain % (is mas %) they take it from all activities (including crafting) then they take it from the decay pool and return the % back. As long as their are people hunting or mining. Their will always be decay to pay
ma. If their are no miners or hunters that would make it that their would be no crafters.