yes rotating the hens is where the difference is. If you were to do it year after year on the same hens, it wears on them. It's not forcing them to stop by not adding light, it's their natural cycle which they have for a reason. It gives them time to rebuild and recoup and be better prepared for the following season.
I hatch year round too, but just from what naturally lays. Dont get me wrong, I'm not one of them "all natural" folks.
I just keep some very high end birds that are not replaceable, and have learned over many years, forcing them to lay year round can deplete their body, make them weaker and more prone to disease, bone structure can suffer from calcium deficiencies, etc...
If you rotate out stock constantly though, just a year of doing is no big deal, it comes for year after year of doing it. Also production style birds differ here too, they are more less bred for this, ornamental breeds arent
Thing is, me at least, I keep very rare and hard to find stuff, so the breeders just arent going anywhere til they die. Once I get a good line going, I keep them, of course I also add each year too, but the primary breeders always stay, just to hard to replace. So in this case, giving them their natural break in the winter is the only route to go for me