I think that is a lot of it, but that doesn't explain all the personal anecdotes I've read.I think this whole conspiracy "theory" took root because of the initial rush of brand new pandemic chicken owners from 2020-2022, who might only have one or two winters under their belts. So these folks have chickens who were in their laying prime, starting to feel their age and really slow down for the first time this winter. They just don't have the experience and knowledge (yet) to protect themselves from these predatory individuals who are monetizing easily debunked conspiracy "theories."
I have seen posts from several different people who say they've had chickens for many years, but that this winter the chickens stopped laying in a way that has not happened before.
So it appears there have been actual changes in the laying of some chickens, beyond what is normal in most years.
What caused the problems is a different question-- whether it was feed, or weather, or stress, or keeping different breeds than before, or caring for them differently, or many other possibilities. I think it's most likely that some flocks had different causes than other flocks, so there is no one single cause, although I don't have any proof of that.