The number of components is not the only yardstick of complexity. Most of the complexity in building a UI comes from state management and how state changes are propagated across the store and the UI.
I worked with Backbone for many years, and I can distinctly recall the hours of frustration I had debugging a UI because it was freezing due to cascading state changes. That was because we were using Backbone Store, which had bidirectional data flow, and when one updated the store, it would trigger a change to the UI, which would change the state store, which would change the UI, etc.
You could argue that the real innovation of React was "unidirectional data flow," but React team made Flux architecture central to the framework, making it easier to adopt good practices, whereas Backbone remained store agnostic and even encouraged Backbone Store which used the observer pattern for many years. I think you should choose a framework that allows you to fall into the Pit of Success, and React was that framework at the time, and for my money, it still is.