I don't play Diablo III. However, it looks like Blizzard's attempt to support RMT in the game with an auction house wasn't successful. From what I can find, it sounds like their official explanation for shutting it down was that it was undermining core gameplay, i.e., it made going out and hunting and looting pointless because if you always wanted the best for your character you would find it more easily in the auction house than going out to get it yourself. (
http://us.battle.net/d3/en/forum/topic/9972208129) This is borne out in articles describing how many players were using the auction house and weren't even spending time actually playing the game after a while. They were just logging on to use the auction house to make money. (Example:
http://venturebeat.com/2014/03/19/m...w-closed-diablo-iii-real-money-auction-house/ )
A lot of people speculated when the auction house started up that it could be used by criminals to do money laundering. As far as I know, Blizzard never confirmed that was one of the reasons they shut it down. However, I don't doubt that it was something they discussed at length.
Korea wouldn't allow Blizzard to release Diablo III there with the auction house enabled because their Game Rating Board viewed being able to buy and sell items won in the game and using the cash-out feature to convert game money to real money as gambling. So I'm sure Blizzard had to look at that angle as well and worry about which other countries might, down the road, also object to the auction house as being a form of online gambling that needs to be regulated.
Blizzard may also have gotten tired of dealing with situations like this where they had to clean up the aftermath after someone discovered a way to dupe gold and 415 players took advantage of it to sell the duped gold through the auction house:
http://us.battle.net/d3/en/forum/topic/8796520380 .
I've also found online articles about people complaining about glitches that caused them to lose their money and which obviously tied up Blizzard's customer service and GM staff doing investigations into those complaints. Some players even threatened to get the FBI and/or other regulatory agencies involved to resolve their complaints.
And lastly, Blizzard also apparently spent a lot of time and money on this court case involving use of the auction house:
http://fusion.net/story/137157/two-...or-stealing-virtual-items-from-other-players/ .
It sounds like, all in all, Blizzard tried and failed for possibly many reasons to implement a way to support players in doing their own real money trading and they ran into many, many problems along the way. It makes it tough for me to believe that many other game companies would want to follow in their footsteps, take on so many headaches, and possibly risk ruining their game in the process and finding themselves out of job, or in the worst possible case, somehow end up being caught up in some kind of "financial crimes" sting and doing time in prison.