Nearly every character in the Sherlock Holmes stories is a storyteller. Or they are storytellers under the narrative guidance of Watson. Storytelling is a crucial part of the entire detective fiction genre, and the Sherlock Holmes stories really explore this aspect. Each Sherlock Holmes tale begins with a new case, which is always narrated by a client or a cop, and ends with some sort of confession/explanation scene, also a story. Along the way to solving a case Holmes and Watson encounter tons of different people and listen to their stories. In a way, the cases that Holmes and Watson solve are like giant umbrella stories composed of a dozens of smaller stories being told by a revolving door of characters.
Everyone in the Sherlock Holmes stories is eloquent for the most part. A lot of this has to do with Watson the narrator, who admits to "cleaning" up a few people's stories for clarity. But the fact that everyone manages to explain everything clearly is also comforting. It fits into the role that the Sherlock Holmes stories play as a sort of fun, literary comfort food where, unlike in the real world, everything is always solved and answered by the story's end.
Though Holmes would argue that detective work is about science, Watson would probably argue that detective work is largely about storytelling; even science itself is a sort of storytelling device.
The presence of journalists and newspaper articles in these stories help to symbolize the important role that communication plays in police work, and in modern society as a whole, in these stories.