I agree to almost every point, but note that in the MVC definition, each of the M, V and C are components, not classes. A component may be composed of several classes. So there's nothing inherently wrong with Rails' approach.
I just think that as opposed to the original idea, people started to stuff way too much into their controllers, which is what makes things messy. I agree that Flux helps enforce the way it was supposed to be.
On the contrary, I find that people stuff too much on the model because of rails. I've found that I much prefer very simple models to describe very fine grained parts of the data and use the controller for much of the tying of things together. You kinda of treat models as 'data components' if you will, mixing and matching them where needed in the view
That's the "Massive ViewController" anti-pattern (or just massive controller, if you're not in Apple land).
Classic MVC is really MVc, with controllers only handling a small set of interactions that are not directly between the Model and View, for example dialog boxes and such.
One problem with a "Big-C" approach to MVC is that whereas models and views are at least potentially reusable, the controllers are dependent on both M and V, and thus both proliferate and are not reusable.
I just think that as opposed to the original idea, people started to stuff way too much into their controllers, which is what makes things messy. I agree that Flux helps enforce the way it was supposed to be.