Yeah, I hate these arguments.
"I want to find my own items, nobody else should be allowed to trade" - Great!
I get it. A lot of people who reach the top of these types of markets in video games are the ones who either have 20 hours a day to play, or aren't playing the game fairly. It upsets people who play legitimately, or people who are unable to invest too many hours into a game.
But if you don't want to trade, don't trade! There's always a way to play the game the way you want to play it, and not force everybody else to do it that way as well.
However, if you take away the possibility of a market at all, then you don't allow options - So to me it's obvious what system should be implemented