The "efficient at-the-keyboard" leveling and "balanced participation towards end-game" model of current MMOGs imposes a severe structural and conceptual limitation on what an MMOG can be. That imposed structure, by its very nature, generates opportunities and reasons for abuse that would not exist otherwise.
For example, bot leveling and account sharing only exist as problems because players must be at their keyboard, under the current model, to advance their characters. This means that people with very limited playtime can either (1) not play the game, or (2) find some means by which to advance their character even if they cannot themselves play very much. If a game offered 24/7 character advancement whether one was online or not, then "botting" and "account sharing" become irrelevant.
An exploit, generally, is finding an easy way to level or gain in-game gold (or the equivalent); if any player can set their character to level or "work" for gold while they are offline, this greatly reduces the significance of most "exploits" that aren't just pieces of bad coding. The same can be said of gold-farming; if the player can set their character to work for gold while they are offline, the value of farmed gold, which basically represents the time players don't wish to invest in accumulting gold, is diminished. In essence, every player can have their own stable of gold-farmers if that is what they wish to do with their characters' time.
While gold farmers might still be able to make some money, the demand for gold as a correspondence to a lack of play-time to accrue gold goes way, way down. Gold would no longer correspond to a lack of time on the player's part to accrue gold, or an unwillingness to use one's valuable online time to farm for gold.
Many of the opportunites for abuse and exploitation only exists in games because of the structural inequalities that generate a market for "online time", either in gold or in character advancement. Take away those structural inequalities, and the reasons and opportunities for much of that abuse disappears.
Also, if there is no set "end game" that is the funneled construct of at-the-keyboard leveling, unique distributor of best rewards, and organized around conformity-driven character skillsets, then the "goal" of most exploits and abuses is eliminated. The goal is simply to personally develop your character over time into that which you desire and interact with others in a setting that has many variant opportunities for interaction.