I heard some more details this morning about a reported but unconfirmed kiteboarder-shark encounter that happened a while back in Florida. It involved a newbie out with a four line inflatable. He had received no instruction from the retailer and was trying to figure things out on his own. He had been floundering around in the water for an extended period when the shark made its presence known. After surviving the encounter and 180 stitches later, the new rider gave up kiteboarding and moved out of the area.
Moral: Kiteboarding lessons really are a good idea. Some reasons are less obvious than others.