Recently I read that Titanfall doesn't ban cheaters, but move them all in the same server, which is indeed an interesting idea.

Now in FFXIV, SE has only been banning hacking bots and ad spammers. They have not focused on banning gilbuyers or normal players with farming scripts. As SE has no problem identifying RMT bots, then tracing those bots' gil movements to identify gilbuyers should be a piece of cake. However, they have not done so, probably because they need the subscription fees.

That's where an RMT server comes in! Forcibly move all gilbuyers and script farmers to the same server, where they can buy gil to their heart's content and continue playing the full game. It's a win-win situation for them, honest players, and SE's wallet!