SE tried do something with gil sellers in FFXI... they removed a large number of accounts... purged untold amounts of currency from the game... this lowered prices considerably but only do to the huge amounts of gil being removed from the game. Eventually legit accounts started to be terminated without notice... major mistake...

RMT started using alternate ways of obtaining gil. This included using "phishing" to gain access to people's accounts. They would mass /tell players from freshly created accounts attempting to appear as GMs, telling players that their account may have have been compromised, with link to a illegitimate web site where they would obtain the users account info and briefly hijack the account.

This would lead player's having their character restored prior to the loss of their valuables. Though limited once per account, this in itself was used occasionally as a way for quick gil. A player could exchange items/gil/etc with RMT for real money in return (i imagine to help with the monthly fee) and then get one quick reset. Of course you only got ONE. Still one was enough.

Regardless of what SE did, they we're powerless. GM's we're completely overwhelmed trying to remove the accounts responsible for the huge flood of spam /tells being sent. In the end, it was the real world economy with in game additions (Abyssea, etc) that moved RMT back behind the curtain. It still lives on, but it influences only those willing to do business with them, and not everyone else.

I think everyone would agree SE's battle against RMT was an embarrassing failure. By cracking down on them they made the game worse for a much larger number of players then if they had gone about fighting it indirectly.