This is not true. My hens are going to be 8 years old next month. All they get is layer feed and they still lay eggs. They aren't missing any feathers.I do not dispute what you are all saying about the conditions the egg industry adopts (it's at least as bad in the USA as here btw), but you are distracting from the subject of feed by looking at the environment. Yes I know both play a role.
But people keep claiming on BYC that a so-called 'complete balanced layer feed' will provide everything a hen needs, and since that is all a commercial hen gets, her condition demonstrates that it is not complete. It is merely adequate for a short life. It does not provide enough for her to thrive; it is just enough to keep her laying eggs until she is about 1 year and 5 months old, at which point she is thrown away, like the ones in the picture.