I've seen this on a few mmo titles now, companies using gold/gil sellers to boost profits and increase registered account numbers. They pretend to hate them, ban them very lazily but in reality they love them as a valued resource.
FFXIV bans RealMoneyTraders, but they do it amazingly slowly and let them shout for hours/days so that they make a profit first. As such the RMT they ban will buy the game again, make new registered accounts and will do this forever. As long as they are left alone long enough to make a profit to offset the cost of buying the game they are happy and will repeat this over and over and over again. Square gets inflated registered accounts and box sales, the rmt sell their gold.
Lots of F2P games do the same thing, they only allow RMT to flourish if they spend money though. You will see RMT purchasing XP boosters or other things so the publishers know they are spending money and they will in return give them enough time to turn a profit..before banning them to repeat the process.
As such RMT are a profitable resource that f2p and p2p titles take advantage of, the days of cracking down on RMT are gone.