Preface - I haven't played WoW for any length of time since quitting at the end of WotLK. I dabbled in the next few expansions, where it seemed gold was overabundant, not sure if that's what killed the gold farmers/gold bots/sellers, but I didn't seem to see any, or even think I might have a use for them. However, with WoW Classic, I can see a market for them to come back. Did Blizz ever put something in the game to eliminate this after WotLK, or was it the gold abundance that destroyed their market. If not, I see the gold sellers and websites coming back.
In the past, if someone accidentally looted something they didn’t mean to in a group, players would have to contact customer support to trade it. In the modern system, players are given a period of time in which they can still exchange loot with others. This is a convenience we felt was worth retaining for Classic rather than making people go through customer support. (Sorry ninja looters!)