it’s a bit of a chicken and the egg scenario there…. are throwers better at 1RM efforts because of their genetic make up and inherent ability to recruit muscle fibres so effectively (which also steered them into a single effort power sport in the first place), or because they got interested in the sport and then spent years developing their ability to deliver one big effort on demand?
a bit of both would be the most likely reasoning!
as for rugby players, it’s probably fair to agree they’re nearest the rowers performance level….
i’ve heard rugby described as a power endurance sport and, if you’ll allow me some licence here, speed x strength x time is a pretty fair description of the game.