In the 20th century the discoveries of piano teachers such as Dorothy Taubman demonstrated that the basic premise behind exercises such as those of Hanon and Beringer is in fact false. The idea of these "5 finger exercises" is to strengthen the weaker fingers so that all 5 fingers will be equally strong. In fact we don't need that much strength to play the piano: what we need is coordination of the different parts of the body. When you have learnt to put the weight of the arm behind each finger, correctly coordinating arm and finger movements, playing evenly will come naturally.
As far as not needing strength to play the piano, maybe if the student has arms like Horowitz or JoAnne Castle.
I have very slight arms and hands (8.5 cm wrist) and after years of practice, still don't have the strength to play a grand piano for very long.
Look at all those child prodigies. There's quite a vogue for them on YouTube: 6, 7, 8, 9 years old but they can whizz through their Chopin or their Beethoven. Many of them practice several hours a day.
I think it is because their brain works other than one of an adult.