Gil sellers are punished much more than Gil buyers.
Most of the figures you see in the MMO RMT ban wave are sellers, not buyers. Of course, although it does catch buyers on a regular basis.
Giving someone a lot of Gil is not against the TOS, so they usually don’t do anything right when it happens. When sellers are banned, they can track and find clear links, but more often, they let sellers continue to pay monthly fees rather than suffer from baking.
Many MMOs operate in this way. World of Warcraft has released figures like this, and I’m using many people for publicly buying gold, and none of them has been punished. Now, wow doesn’t even issue the number of RMT bans. To be honest, I don’t think they care anymore.