Pretty much. They said at the time the restriction was b/c that they didn't want RMT to be using mogmail to give out gil after it was sold.(I was there) I don't know if there IS any rmt anymore since this game isn't so popular (I think most went to XIV) but on the other paw, I don't think the restriction on mailing gil between charas on the same account should be there to be honest.
Also they may of been sending it between their charas on a account, I didn't know that, but not being able to mail it to another account would still mess them up I think, since back before they added the restriction, that was how they used to do business. I think they do direct trade now? Mind I never paid too close attention b/c I hated RMT and never bought gil, but if you've played as long as I have, you can't not be aware of their presence.