Regardless of the circumstances, there are always some people who seek an unfair advantage. With MMORPGs, it's mostly people who find a way to generate more in-game currency they can ffxi gil for sell to others for real dollars. In FFXI, the development team and the GMs discovered a group of players who were finding ways to generate large amounts of ffxi gil ign. They were then turning around and selling it for actual money, producing an influx of gil across all of FFXI's Worlds and driving prices higher.
The Devs and GMs did not take this issue lightly. After an investigation, they permanently cancelled over 700 accounts. As a result, over 300 billion gil was removed from FFXI, driving prices back down to more sensible levels, or at least as sensible as anything can get in an MMORPG. Either way, it's clear the world of Vana'diel is not a place to be messed with, especially by gil farmers.