- K3K only drops sets
- TA drops Sets and SU
- Fauzt drops Sets, SU & SSU
- Duncraig drops Sets, SU, SSU, SSSU
There are many non desirable outcomes of this scenario.
1) If you are an experienced player who wants to efficiently farm sacred uniques you just roll the build that is most efficient for the highest tier uber. It doesn't matter if this is duncraig or fauzt or anything else. There is always some build that excels in clearing a level with cheap equipment. So what happens is you know that if you farm anything else just to break the repetitiveness or for fun you will not be getting the best items, so you feel like you are wasting your time by not sticking to the same area - it just leads to more boredom.
2) New players get locked out of the trading economy. Currently if you are not that good you can still farm destruction bosses, do Nihlatak runs or maybe spam Tran Athulua with your Trap rat. Even though these are not the most efficient farming locations you still get enjoyment from the activity because you know that at any moment you can get something godly. Otherwise you feel like your time spent doing this repetitive activity is not fun and stop playing.
3) You remove the excitement of seeing a sacred unique drop. Right now you can go outside in the destruction Blood Moor, kill a flit and get a leather gloves sacred unique. The chance is low, but it might even be demonic touch! If drops were localised and you know that these gloves are only geglash's dusters - you will not care about the sacred unique drop. Sacred uniques are the top tier items for a reason - getting a unique version to drop should always be exciting. The moment we allow the average player to not get excited about a sacred unique is the moment a lot of people will stop playing the game. (why do you think D3 tanked on release? Yes it was not the simplified gameplay or the difficulty - it was because 99.9% uniques were vendor trash)