JSF was designed in part by the authors of Struts to create a "Struts" that did a more accurate implementation of MVC (Struts is technically "Model 2") and to get rid of all the interface and subclass dependencies. The idea being that POJOS are more re-usable and easier to unit-test offline than framework-dependent code. Which is why I chant endlessly:
The more JSF-specific code that is in your JSF webapp, the more likely it is that you're doing it wrong.
The other thing that the Struts folks didn't like about Struts was that you had to define too many classes for each component. In JSF, you define a view template file, a backing bean (model), and that's basically it. There's no separate "action" class to transition data in and out of the MVC part of the webapp, just POJO methods that are defined in the same class as the POJO model.
https://coderanch.com/t/625642/java/Struts-JSF
