At first glance this seemed intuitive and obvious. But upon consideration it seems like the processing involved in unstructured learning would be far more computationally intensive than low level sensorimotor skills, even once you have worked out how to do it. Finding statistical relationships between large numbers of concepts and sensory inputs just doesn't scale well compared to doing a bunch of calculus to predict an control movement of the body. Much of our high level reasoning relies on this system - not just on shuffling things around in 7 slots of working memory.

There is something to the paradox but you have to be rather careful when describing the distinction. "high-level reasoning vs low-level sensorimotor skills" may not be the best way to look at the distinction. "Conscious vs unconscious" is somewhat closer. It is also worth noting that even among skills that haven't evolved over hundreds of thousands of years in animals - the ones we learn with 10 years of solid practice - it is the unconscious skills that use the most computational resources.