If you stop the frame when most footballers are engaged in action, their arms are in what shit refs would decree an unnatural position.
There is a diffefence between that & leaving your arm in a position to deliberately block.the ball, which is what Piquet just did. Same as the difference between using your arms to jump, & extending your elbow to deliberately hit someone in the face, having already jumped. Like Fellaini does.
Micha Richards at Anfield: not handball no advantage no intention.
Piquet= left his arm up on purpose. Own fault. Pen.