Data Literacy is essentially the ability to read and understand data, much as one might read and understand a magazine article. The primary advantage of having the bulk of the staff made up of people who are data literate is that it reduces the need for data scientists. People on staff can handle many of the data issues that arise.
Staff members can critically assess data, to varying degrees, and fix problems or find business insights. This is why it is important for most people in the organization, not just the data analysts, to have access to data, and a basic ability to read and use the data.