Currently the Diablo 4 itemization system makes no sense and has many flaws. There is no clear vision of how they want to define the game with its systems.
They wanted to do a mix between optional trade and solo self-found but this system didn’t work due to smart loot. Because of smart loot I can only find things of my class and obviously I keep the things I find for myself because they are useful to me, especially because of the tempering system which can cancel items with 2 or 3 greater affixes that I find, and which are extremely rare, so I have to find more than one for each equipment slot to hope not to brick the item. This system leads to nullifying the trade, which is present in the game and is a feature of the game, because by only finding items of my class I will never tend to trade with someone to make gold and buy an item as I want it because the items that I will find will always serve me. The only way to make trading meaningful is to remove smart loot so I can find items of other classes, and be able to trade items I don’t need for gold with other people. I think that with the current smart loot system, which makes trading useless and without the possibility of resetting the tempering (perhaps a reset with 4 or more stygian stones, a rare and tradable material, could be an acceptable thing) makes, not only a lot boring and unrewarding to find items, but also extremely rng the entire system. No trade due to smart loot and no tempering reset, perhaps making it limited in exchange for many rare materials, they make a bad match.
So I ask myself: what is the point of introducing a trading system with tradable items if there is smart loot that forces you to keep the items you find for yourself? And therefore never to trade