This mechanic, exists in most and by most I mean 90% of games so most right ? yes.
Why, because because a class "shade" has OP damage, and lets face it they do, I play one, and yes still see that they do.
Pros = no more can someone using a shade out damage someone/s and win loot rights even if they don't start fighting until another player or team has been fighting for 10 seconds before they deem to sneak/back stab instantaneously and win the loot despite doing nothing more than using sneak and then attacking, when they feel like it.
Cons = shades are that one v one class they survive by damage, taps and drains but against multiple adds they don't do as well.
In the world of AO, perhaps the % damage should include the adds around the desired dyna, that is team/soloist goes in, kills all the adds and keeps killing them as they wait for the dyna spawn.
Now if shady shade wants to come to the same dyna, they would have had to contribute to killing of adds in addition to killing the boss/dyna.
No more sneaking their way in, waiting until the fight starts then using OP damage to get loot having done the minimum of work to get to the dyna.
Discuss.