It may just be semantics...our coop is built on deck blocks. It's "off the ground" but I wouldn't call it "elevated" either. It's a normal 8x10 walking building that happens to sit about 9 inches off the ground. It's build that way because of our yearly snow totals and the freeze line is so deep.
So, @Jeanw may be meaning that they would not set/build a coop directly "on the ground", but they could also be meaning an elevated coop (built on stilts and typically not a walk-in)
I personally wouldn't elevate a coop less than a foot, preferably 18-24 inches -- enough room to admit light, air, and chickens. A low gap between the ground and the floor is a perfect habitat for rodents and other pests.
If I were building a new, small coop in this current situation with wood so terribly expensive I wouldn't want to spend the money for a floor -- though I do like the convenient height for egg collection and cleaning of my Little Monitor Coop.