If it seems like overkill, it probably is. I could see myself going either way. If your login flow is simple and unless (or until) you find yourself needing to add setState all over your app to deal with login business logic, don’t use BLoC for that.

That’s something I didn’t emphasize enough in the talk nor this article: you will have widgets in your app that will use setState and/or ValueNotifier even if you decide to use BLoC. For example, doing a custom fade animation using BLoC is most probably overkill. Not sure about login screen — it could benefit from having a BLoC in some cases, but in others, not so much.