While it was a fun concept, nowadays it really wouldn't work not only because of the playerbase wanting to buy/sell stuff ASAP, but also because if it was the only way of buying and selling, people would start using bots to sell and buy. Prime example for this is Oldschool RuneScape where you have to manually trade a person and look up their offers to buy and sell, and while it might -seem- "fun', all it is is annoying to buy and sell small quantities of items. Besides that, there are bots buying and selling as well which defeats the purpose.