Why would any one trade materials if materials are burnt for progression? even for people who whant to train a character for pure combat.
The only trade is possible? is for BP's and carts, and that's it, with this current skill decay system, which is useless , this is my point of view.
You created decay for need of materials but you also created this need for not to trade but use materials for your self, which breake trading with others.
Either you have to create separate system for combat progression, or remove decay system.
I do not wish to get in a hostyle argument, instead, I want trading in game to be usefull, and simply saying "NO" is not going to help either way.