“ they cannot scale”? Again, this is just wrong. Stateful widgets are everywhere in Flutter. A fundamental building block of every app.
“ It will be very difficult to pass state of an widget from one screen to another” — How would it be easier with a stateless widget? How would you pass state if there is no state?
This is not just about “improvements”. What you did here is the worst beginner error.
At this point I would recommend you to unpublish the article until you fixed all these blatant issues.