This is the most prominent in-game rule. Perhaps every person playing MMORPG knows about this. Selling of in-game currency and accounts for real money is prohibited and will result to permanent ban. The same rule applies to trading or exchange of accounts.
Server owners have good explanation for the rule. Some sellers are scammers. They ask payment in advance but have no intention to give the account / currency or items. There are instances where seller will report the buyer after the transaction in attempt to get the account back and sell it to another customer.
The second reason. Game servers are business. They are built to earn real life money. Most games are free-to-play. Play it without any fee except for computer rental or monthly internet and electric bill. But MMORPG have Item mall. It provides enhancement items, costumes, pets and power ups. Mall items are bought using real currency.
Selling of game accounts/items reduces server income. A new player probably wants to acquire mall items using real currency. By buying a strong and leveled character from a quiting player, acquiring mall items is unlikely. In addition, account sellers are not item mall buyers. Most of their items are earned through farming.
