Aren't you missing OP's point entirely? Which is: If the LLM didn't have useful information it would still give you an answer... Helpful or not.
That's false. The LLM will only answer competently if it was trained on that data; and if it has enough data to make the correct connections between your question and the "correct" answer.
In the case of this article they're specifically saying the LLM has limited training.
How would you know if it didn't?
A prudent strategy, but I'm not sure how prevalent it is in the general population. (Or even if people do look at multipole "sources", they're in a self-reinforcing echo chamber that may reject contradictory information.)
I now read the absolute dumbest shit on HackerNews when it comes to AI. "It can't write code! It's always wrong!" And no one ever demonstrates any of it, even if it is counter to the experiences of others.
I'd feel bad if most of these people weren't total jerks...