One comment that made me think on HN a while back is something akin to "The average IQ is between 85 and 115, therefore AI will be akin to friends with IQ's between 85 and 115 giving you advice". So not that useful?
I also don’t think you need to remove the dumb comments from the training material anyway. The AI could be able to simulate either someone of 80 IQ or 180 IQ, producing output consistent with both personas.
Accurate information is also over represented because you can be wrong in far more ways than you can be correct. In other words the wisdom of the crowd is in part the 10% of people that know X all match each other while the other 90% is all over the place.
And ignorant person could have a very high IQ still be very ignorant.
LLMs may not be "smart" but they know a lot.