It does depend on what you are comparing it with.
Scratch keeps chickens warmer than a complete, balanced food: myth.
Scratch keeps chickens warmer than no food at all: true. But most of us are not making that comparison! (Apparently that was fairly common a century or so in the past, when many people expected to forage for all of their own food. Not much food was available in the winter, so giving the chickens some scratch-- or anything else-- really would make a difference in keeping the chickens alive through the winter. Starving chickens are more likely to die in the cold, just like starving chickens are more likely to die of most other causes.)
