Duping is such a nightmare for everyone, not just the players, but as much if not worse for the Devs. It's like a cancer that just keeps eating away at you. And just when you thought you had gone into remission, boom, there it is again.
Players cannot begin to understand how much time and energy we devote to tracking down and banning dupers, removing illegal items for the game and finding ways to fill the holes that allowed the dupes to occur in the first place. But dupers are like cockroaches. You kill one, 10 more come out. Some of them are easy to catch. They're amateurs spotting a pot of gold and in their greed allow themselves to be caught red handed. Those are my favorite as they're not only easily disposed of, but they also usually cause the least damage to the community.
The Dons, the Master Minds, those are the ones that suck. They are hard to get. They are speedhacking little roaches, that only come out in the dead of night and are pretty much immune to most pesticide you can throw their way. You will never catch them alive. They will throw their minions under the bus, but you won't get your hands on them. They're the ones that really hurt the community and the Dev team and the game. And just like the Godfather, you often have to resort to nailing them on tax evasion. And yes, sometimes this means you need to let the minions run around unhindered a little longer just so you can work the trail back up to the leaders.
Each time, we have to divert development time to track down dupers / exploiters, fix the loopholes, remove the offensive items and investigate their accounts to gather sufficient proof to proceed with a ban. This translate as delayed publishes, canceled new content, lesser bug fixes. For the players, it means their legitimately acquired items losing value while inflation rises. For new players it means a tougher barrier to entry. For the game in general, it means serious imbalances between the haves and haves not, accelerated depreciation of entire game systems because the reward that gave them their purpose is now flooding the market.
So make no mistake: Devs have NOTHING to gain by allowing dupers to run rampant. We don't spam how many people were banned or when we are banning people. That doesn't mean it's not happening on a regular basis.
You would be surprised to know how many people were actually banned in the last wave. What boggles my mind is how eager players are to believe someone claiming innocence. We also have nothing to gain by banning innocent players, quite the opposite. Do mistakes occur from time to time? Sure, no one is perfect. But you shouldn't assume that because someone says "I didn't do it" means they really didn't. Anyone who gets caught speeding will likely try to sweet talk their way out of a ticket. If it works, WOOT! If it doesn't, oh well, was worth the try. That doesn't make them any less guilty. Difference is, the guy who crashed into a tree because he was speeding won't make a fuss, because clearly there's no getting out of that one. Both as guilty, just one more obvious than the other.