Building flexible Rails apps above the obvious '15-minute blog' requires a myriad of controllers, models, views and other stuff. Moving as many as possible of these bits and pieces into the DB will liberate the application and make it able to serve diversity better!
Models could be persisted to the DB and either eager- or lazy-loaded on web-server start/reload.
José Valím showed us in CRA how to do away with the file-based template, and I know from personal experience that REST and proper routing does make the controller easily implodeable to a single controller (handling authorization, authentication, state_machine and polymorphic associations)!
I nowhere near claim to be in the know ruby-/railswise! I'm not even a good developer/coder and building stuff takes me for ever to get right, and I constantly forget the syntax - and I'm not part of the RoR nomenklatura, not even by a long shot!