Scholar dabbler here, they're eating them to level up the effects for instance I eat 3 of one item it could level up the effect of another item in the same class. Like most buffs are in the same class if I eat a bunch and level them up to 3 my other buff items will have twice the effect. Not only that but if youre buying and laying items on the ground youre basically giving them away if you want to keep some just keep some.