> You must rely on your own internal model in your head to verify the answers it gives

This is what significantly reduces the utility, if it can only be trusted to answer things I know the answer to, why would I ask it anything?

its the same reason I find it useful to read comments in Reddit, ask people their advice and opinions.

I have written about it here: https://news.ycombinator.com/item?id=44712300

Verification is often easier/faster than coming up with the answer totally