When I was one of the younger owners, some 25 years ago, we lobbied for a rule change to allow the helm to sit on the side deck. At the time the older members voted it down at the AGM for fear of making helming too athletic for them. Now I am an older member myself and I still support the idea of the helm being allowed to sit on the side deck. As Andy says it’s so much easier to see the jib telltales, to rotate the torso as the boat heels, and to lean back to look at the main and windex without cricking your neck.
it’s about comfort and ergonomics not ballast on the rail. For that reason I am firmly against the crew being permitted to sit on the deck.