ArenaNet Game Designer Jon Peters contributed an explanatory post on Guild Wars 2's forums as part of a sizable thread examining the recently implemented diminishing returns system for karma and dungeon rewards, which increasingly limits gear tokens and karma rates as a measure against exploits.
"These systems are put in place to protect the economy from botters and exploiters," Peters wrote. "We will close exploits as quickly as we can. These thresholds help create a safety net to keep the economy safe when we aren't there to deal with the offender."
Peters acknowledged the need for ArenaNet's vigilance on balancing and patching the system to avoid punishing legitimate grinding sessions and target actual bots, writing, "We believe some of the threshold systems are just too harsh empirically, and we'll be adjusting those systems within the next few weeks to ensure that fewer legitimate players are being impacted."