I agree. Why does so many pianist (read: teachers who, most of the times, are terrible pianists) insist on having tension in the wrist and "scratching" and "gripping" the notes. How is that helping anyone?
We have arms, and a back, why do you want people to not using them? Try playing above mf in a high speed and gripping and scratching.
That doesn't make any sense at all. It's like eating, but only with your toungue, and not using your teeth.. Yeah, it's really that stupid.