It’s not actually about being specific per se - it’s about overtly mentioning details that are already assumed from context. Grice’s maxims of quantity and relevance say that speakers only provide information when that information is important in some way and relevant to the discussion, so providing information that would otherwise be assumed means that information is actively relevant to the conversation in some important way that warrants it being mentioned.

There’s a great video by Tom Scott on this exact topic.

Talking like Mojo JoJo is always fun

Now I want to have a Jackie Daytona style NPC that is obviously hiding something, but completely irrelevant to the plot.