What do you mean by "efficiency", because I would think that guaranteed science from many Harbors via Free Inquiry in the early game coupled with a massive boost to production and gold in the mid/late game through strategic use of renaissance/industrial policy cards would be pretty damn effective on Deity.
Unless you mean a turtle strategy... sure I guess. Korea is pretty straight forward and reliable. That's the benefit of having relatively one-dimensional civilizations and why I don't think every civilization should have 20 effects like the one in GS. Some people just want to do one thing and one thing only
I'll admit I have only played Deity on Standard in Civ5 mostly with Vox Populi... (In Civ6 I mostly play Marathon games so my perception is skewed) but I don't see how Korea would be that far ahead in practice in the hands of presumably good players.
... unless the only reason they won Deity in the first place is that they skated through with ...
Ah I get it now.