If you want to draw a parallel between kayakers and some other group, I
think those bicyclists who pedal down the middle of the lane at 5-10
mph in a 45 mph zone and flip off every motor vehicle that dares to
pass them would be closer kin than PWC'ers.

Well, there's quite a difference between a bike trying to make use of a road
and kayak. Most states give cyclists the same rights to use the roadway as
a vehicle, as well they should. It's not an accurate comparison.