Per Jeremy:
Another spin on the same idea is that with 0 offset, both blades might hit
the wave at the same time. The result can be quite a jolt.
With some offset, this is hard to do.

Working on that.... It also would seem that with the offset, if one blade
accidentally hit the wave face - as in the paddle being held out horizontally -
the paddle would pivot around the paddler as the other blade sliced into the
wave rather than clothes lining the paddler.
--
PeteCresswell