Having a list of references is theoretically enough to accomplish this, but in practice it’s too much work to rediscover which reference contains a particular piece of information, much less where that information is within the resource. In practice, having in-text citations, especially when they include page numbers, make me vastly more likely to revisit the reference when I need to and overall saves me a lot of time and effort rediscovering the information from scratch. And this all goes double for writing read by other people, who have a whole host of other reasons for wanting to read the original references.