I can't find a clear answer in what little searching I did.
If you did this via simple linkage lengths, you would have a positive camber in the vehicle upright position where you would have to take the outside wheel through vertical on turn in. That would be clearly a bad thing I think. Obviously you could devise a camming linkage or actuator to better control differential lean of the fronts. My gut says that the free lean balances the handlebar torque / centres the steering effort and that the outside wheel just turns a little faster with no scrubbing.