The root of learning music, of making music, including at the piano, should be joy. Once joy is firmly established, and, well, enjoyed by the student, then it's time to layer on challenge, and complexity, and the rewards that come from struggle and hard work. If we begin with complexity, right and wrong, errors and mistakes, struggle and hard work, we run the risk of removing the joy from music-making early on, and possibly for life.
In our society many (most!) enjoy listening to music, but too few enjoy making music. As a music teacher, I've decided to own that. Almost every day it seems I hear someone lament that they are "not musical." Often they tell me it's a teacher that told them so, a teacher that gave up on them, or that they gave up themselves because it was too hard.
How is it possible that anyone is not musical? It's not! How is it possible that making music is too hard? It shouldn't be! Our primary function as teachers should be to help our students experience joy in making music from the start. Everything else, including getting better at making music, seems secondary and conditional. If not, it's putting the cart before the horse, and of course both horse and cart get hurt.
So how do we help all students find joy in making music from the very start? We meet students where they are, we learn what our students' goals are, we help them achieve their goals, we help them make music they love, we offer challenges when they are ready to accept challenges, but we move at a pace that keeps the joy alive!