From what I've read, chickens 200 yrs ago (and further back) didn't lay much in the winter. Part was genetics - we hadn't yet bred the amazing layers that we use today, commercially (and at home - we have some white Leghorns in our yard now). Part was technology and knowledge - we didn't know that lighting the coop meant more eggs in the dark winter (and we didn't have good or cheap lighting then, anyway). Part was food quality: a chicken can't lay if its diet is missing elements or is too low in calories or protein (or calc.).
It was hard on farmers in cold areas back then, especially in the Middle Ages. In winter they often had to slaughter a lot of livestock for lack of feed, keeping just enough to breed again in the spring. Hard to feed your chickens wheat or oats if you're starving. Improvements in food production & storage (and fodder) meant being able to keep more animals alive over the winter - and a larger herd or flock the next year.
In the 1600s there was an agrarian revolution in much of Europe (but not France - part of why they had their revolution, ironically). Crop rotation, seed drills (the real Jethro Tull!), clover, and so on - food production soared compared to the past. Also new foods were tried (from all over the world) - maize - root crops that could be stored in root cellars or just in the fields - potatoes = more calories per acre compared to any grain, at least back then (may still be true now - also sweet potatoes are high in calorie per acre).
Still, even in the 1800s, we had low egg production in winter. Chickens had trouble foraging (snow, or when the snow was not on the ground, few bugs - maybe seeds or roots - maybe cold loving weeds). Also, as mentioned, genetics and things like lighting were still waiting to be worked out to the extent we have today (some breeds today, if well fed, don't even see winter as a speed bump - and I've read, don't even need coop lighting - but not sure about that).
If you're laying eggs for your family and have other sources of income, you can afford to try different stuff and risk missing eggs. If you're making a living off chickens, you can't afford many mistakes at all. Your margins are usually very tight. Lots of costs in agriculture. This is one of the reasons some people go for the hyper-nutrition, and it seems to work (a whole mess of "experts" back it up, too). That said, other ways are being made to work, too (organic, free range, etc. - but pasturing chickens in the snow? I kind of doubt it). Anyway, there are reasons farmers do what they do, even if it doesn't make sense to us (and even if there are long term costs). They continue to feed the nation (and a lot of the world) - I've lived in other countries besides the US (food can be insanely expensive in other parts of the world!). We should be thankful.
I hear you, though, when people say "you must feed this or that" - it may not always be right. I'd look at it this way: I think chickens evolved to eat a varied diet mainly of bugs, forbs (weeds and young plants), and seeds - and little animals - and maybe some scavenging (many non-dedicated scavenging animals will scavenge if the opportunity presents). There's also "they can survive on this" versus "an optimal diet for growth, health and egg production (or meat growth)." All stuff to keep in mind. Good luck figuring it out!
