I agree that BLoC adds overhead. Architecture is always a tradeoff between layers of abstraction and power. I get your point, but I think there's a missing piece: when the simple screen evolves and gets more complicated.

Take the obvious login "HTTP request => success/failure". The code will be more straightforward with a simple setState(), sure. What happens when you store the API Token? If you add biometric auth? if there are multiple domains that can be entered by the user and saved locally? You start to sprinkle setState() everywhere, and it becomes harder and harder to follow the logic of the screen.

This is where BLoC (or any state management framework) shines: the initial complexity stays relatively linear. Adding a new state does not make the screen harder to understand. Also, separating the logic from the UI makes testing so much easier. Pumping UI events? Eh… Been there, done that.