Everybody used to ski race-narrow skis in powder, perhaps ones with lots of flex (and bounce), and these did great for many, and me too in powder for.......40-50 years?
The first Head Standards (early sixties?), for example, were soft enough to be good in powder (of almost any depth). My other favorites (from ~1987?) were also narrow, some Atomic freestyle dance/ballet skis - they were otherwise very flexy, good trampolines in 3+ feet.
I admit, I sorta struggled on my old g.s. race skis in powder.
It isn't really a question of whether a certain width ski will work well (with the right skills). For example, Nordica Enforcer 100s "work" very well there, as well as anything in that width, to me. But they are down in the snow, whereas a pair of K2 Pinnacle 118s (Seth's ski), has a very similar "carve" feel in 2+ feet as the Enforcers, but, to me, otherwise a different feel and different float in powder - and more fun. To me, Enforcer excellent, Pinnacle 118 way better, subjectively speaking. And ditto with many other fatter skis: (for me) 184 Volkl Katana 112, 186 Atomic Automatic 117, 189 K2 Pettitor 120, etc. For example: (From Skiers Junction gear reviews)
"2017 K2 PETITOR SKI
Edited by ski otter - 7/24/16 at 3:29pm
"Featuring a new tip Rocker radius to pump out more shovel, the most well-rounded pow ski on the market is ready to take on any feature. Built with the stiffness flex profile in the Shreditor series and combined with Powder Rocker, the Pettitor 120 Freeride Ski thrives in the deep but loves to devour crud and firm snow conditions as well."
Radius: 22m @ 179
Construction: Triaxial Braid, TwinTech Sidewall, Fir/Aspen Core
Binding Options: Flat
Features: Powder Tip, Skin Grommets Tapered Tip and Tail, Swap Base
Baseline: Powder Rocker
Skin Type: Trim-to-Fit
Sizes Offered: 169, 179, 189"
Exactly. [I apologize, this post is partly to add skiing pizazzz to my drab summer hiking/biking existence.]