"Overwhelming expert consensus" implies that you know who is an expert so I don't see how it helps an idealized clueless average citizen who arguendo cannot judge accurate information from mis- or dis- information.

Also, you have heard of "100 Autoren Gegen Einstein"? Obviously people who bring that up in an actual conflict of ideas are almost certainly not Einstein, but how do we know, and if we think we know who is right and it is the majority, how do we refute the claim that polls don't determine truth?