You want my personal opinion? Remove rewards from marks entirely, and make them all elite bills.

The reason this goes on is because people are literally farming them. No one waits for others, so everyone's pulling the mark the instant their group arrives. Even if you're there when it spawns it can be difficult to get full credit purely because of how many people are attacking.

Hunts were poorly designed from the get go, and it's because they always offer a reward that this goes on. Kill the rewards, or at least make them harder to obtain, and you've solved the biggest issue. If nothing else, it means the hunt parties will rotate across zones since they will no longer be rewarded for killing the same mob twice in a week.