first, to prevent botters and sellers from duping and buying and selling mats for real money,
second, it will prevent the 4x player gives 4x the reward due to sharing materials over a single player player… you dont even have a dedicated group finder in the game so it cannot be meant to be played that way by default for maximum gain…
and 2 other things, add a loot filter and infinite stash tab, and your game will already be not only better but it will rise in popularity really fast,
and the last thing, yes its not 2 but 4 :P, stack aspects together when you find them and upgrade them for permanent crafting, so a per rolled aspect can be slotted in an aspect menu where you previously had weaker version, and then making a reason to farm aspect and dump them instead of your stash, collect and upgrade aspects in a seperate tab for permanent unlock