Often it's simply for clarification.
For example...
Person wrote:
"Where is the blue squidgee?"
Human wrote:
"What is a blue squidgee?"
If "Human" replied, "it's on the table." without knowing what they were talking about, it wouldn't help "Person".
Or...
Individual wrote:
"What's your social security number?"
Somebody wrote:
"What do you need that information for?"
"Somebody" may decline to answer the question if "Individual" doesn't have a valid reason for the request.
Or...
Waiter wrote:
"What would you like?"
Restaurant Newb wrote:
"What would you recommend?"
That would save time vs. "I don't know." and could give you an interesting option that might have been overlooked.