To be honest I don't see any reason why someone need to buy an account except participating in Bounties or Signature campaign, any opinions?
There shouldn't be any reason as all possible reasons had been eliminated. Before the introduction of copper membership, project wanting to make an announcement on the forum, buy account to do so since newbie account weren't given the privilege of posting images but now things has changed as with just few dollars you can bypass most of the newbie restrictions and make your announcement.
Of course, most persons buy account just for the sake of participating in bounties and signature campaigns. Knowing that ranks comes with certain benefits and as such, it has resulted to a lot of farmed accounts in the forum. Mostly grown in the local boards if you ask me as, one can neither tell completely what goes on there if you aren't from that locality. Even a Google translation won't give you a complete thought on the discussions.
Forum not to have made account buying a detestable rule, I suppose was due to the copper membership kind of buy and white listing or I should say an upgrade on a new account. Not farmed and sold accounts. Perhaps, there should be another name to classify buy a copper member and the actually account farming and sales. So one can be regarded as a detestable crime and when found wanting, the accounts would be punished with a forum rule. Just as it is done in cases of plagiarism.