Rails is an awesome web application framework and it used by a lot of companies to ship features fast and iterate quickly. Developers also love the ecosystem and the stability that the framework offers. But it is not without its criticisms. One of them, which I experienced in my professional work as well, is its lack of direction on how to structure business logic.
The introduction of Concerns provided another layer where this logic can be extracted from models and controllers, but I think that this is still lacking, especially as the complexity of the application grows over time.