I don't see why this theory needs to involve fraud. Rather, it seems like simple math, the only kind I can do. If you bring in a greater number of writers behind the paywall, without, evidently, a comparable number of readers, there will be more content competing for the readers who are here. More people wanting a piece of the pie without the pie getting much larger. That's not fraud. There's just so much people can read.
I have definitely seen my readers go down, which explains why I'm making less money. And while I'm willing to consider the possibility that people just don't want to read my work, why now after four years?