Why don't Subaru just use a simple reliable central diff lock how they had it in 1988 , dose this prove that the cars running gear is not strong enough, so that's why it has to be a gimmick AWD system.
The most simple explanation is that in Snow and Dirt mode all the power is directed to the wheel with maximum grip and the other wheels are not spinning. in Deep Snow and Mud all the power is equaliy distributed between all wheels and they all spin even if not touching the ground.
