Про суп это шутка была, но если нужен серьезый ответ, то весло дает физ подготовку. А она нужна. Как писали point 7 у себя в блоге:
Is it difficult and physically challenging to sail at this limit? NO. As explained it’s all about the right balance of the trim. It’s not like running where to go faster it’s more exhausting. We all agree that is not that we windsurf instead of going for drinking tea at the bar, so a bit of sport needs to be done…(otherwise there is always kiting as an option)…