Just throwing in a different perspective. A quick disclaimer though: I am not, and likely will never have, Necros or any AFK farmers, as I just have no time to create one.
Right now, DP (Varena server) is almost un-enterable: it now has 6 channels, but all of them are inhabited by at least 2 (sometimes 4) reapers. Even mid-level folks like me (currently 242) dare not venture there, as one hit from any attack of these reapers automatically drops all of the gems that you have farmed.
Compare this with the regime where you have AFK farmers dominating the map. Then, at least you get to share (steal?) from the drops and can actually come out with a decent amount of gems after an hour’s worth of farming/looting. Another disclaimer: I am well aware that this is only possible when the farmers are actually AFK, otherwise they dominate the map.
Another scenario: a warlock who endlessly casts Invocation in the entire map. With this guy inside DP, expect a loot reduction of at least 50%. 2 warlocks can practically milk an entire map in DP and exclude everyone else.
If your solution is to ask GMs to put grim reapers, well congrats, we have them now. And DP is practically un-enterable (perhaps not until a group of high level toons band together to kill reapers).
Now tell me, how is this a better scenario?