فَلِتَرْبِيَةِ الْفَائِدَةِ
That is, to increase the informative benefit.
When the listener needs to know more than the bare occurrence of an action, an apt complement can increase informational value. «حَفِظَ فُلَانٌ» says that someone memorized; specifying the text, time and location may make the report useful for a particular question.
The point concerns appropriate qualification, not indiscriminate accumulation. Details that do not answer the occasion’s actual question may burden rather than improve the discourse.