This was considered in the paper: "Some point to a dearth of ‘low-hanging fruit’ as the readily available productivity-enhancing innovations have already been m

This was considered in the paper: "Some point to a dearth of ‘low-hanging fruit’ as the readily available productivity-enhancing innovations have already been made19,27. Others emphasize the increasing burden of knowledge; scientists and inventors require ever more training to reach the frontiers of their fields, leaving less time to push those frontiers forward18,28. "