Take a digital product like a Map, for example. When used in 'searching for address now' mindset, it delivers more value the less time and attention it takes up from the user. The user is on the move, probably walking, driving or cycling, maybe coordinating on the phone with a friend, maybe carrying something ... it's a resource-poor context. The user does not have much time or attention to spare, as it is taken up by so many other demands. So the lesser she has to refer to the map, and the less mental attention it demands from here to reach her destination, the more effective and valuable it is perceived to be. Attention is a result of the cognitive load demanded by digital products.