It's an effect of it being trained on internet data. People generally don't post when they realize they don't know enough about a topic (or post total nonsense, but looks like the dataset team has been able to filter that out). There's almost no text on the internet where there's a high-quality analysis based on what the writer knows, while being clear about their knowledge gaps. Either they look it up and fill in the gaps before posting, or simply decide not to post.

Maybe high school and college students' closed-book exam answers could be added to the training dataset? That might help to some extent.